Method of lowering flash point temperature of fixed catalyst bed during synthesis of acrylic acid through two-step method for heterogeneously catalysed gas-phase partial oxidation of propylene

FIELD: chemistry.

SUBSTANCE: present invention relates to a method of lowering the flash point temperature of a fixed catalyst bed during synthesis of acrylic acid through heterogeneously catalysed gas-phase partial oxidation of propylene, in which a) at the first reaction step, propane undergoes heterogeneously catalysed dehydrogenation to obtain a product gas mixture 1, b) a partial amount of components in the formed product mixture 1 which are different from propane and propylene are converted to other compounds if needed and if needed a partial amount of components of the product gas mixture 1 formed at the first reaction step which are different from propane and propylene are separated, wherein a product gas mixture 1', which contains propane and propylene, as well as compounds different from oxygen, propane and propylene, is obtained from the product gas mixture 1, and c) as a component of the initial reaction gas mixture 2 at the second reaction step, the product gas mixture 1 or 1' undergoes heterogeneously catalysed partial oxidation in the gas phase of propylene contained in the product gas mixture 1 or 1' to acrolein, where the product gas mixture 2 is obtained, and d) temperature of the product gas mixture leaving the second reaction step, if needed, is lowered through direct and/or indirect cooling and molecular oxygen and/or inert gas is added to the said mixture 2 if needed, and e) further, as an initial reaction gas mixture 3 at the third reaction step, acrolein contained in the initial reaction gas mixture 3 undergoes heterogeneously catalysed gas-phase partial oxidation to acrylic acid, where the product gas mixture 3 is obtained, and f) acrylic acid and at least unreacted propane and propylene contained in the product gas mixture 3 are separated from the product gas mixture 3 in a separation zone A an then returned to at least the first of three reaction steps, where i) the second reaction step is carried out until achieving propylene degree of conversion Up ≤99 mol % for one-time passage through the zone, and ii) the third reaction step is carried out until achieving acrolein degree of conversion UA ≥96 mol % for one-time passage through the zone. The method involves at least one separate selection for components different from propane and propylene, which contains propane and propylene in amount ≤5 vol %.

EFFECT: low temperature.

39 cl, 1 ex

 

The present invention relates to a method for producing acrylic acid by heterogeneously catalyzed partial oxidation in the gas phase propylene.

Acrylic acid is an important monomer which as such or in the form of its complex Olkiluoto ether is used for receiving suitable for the production of, for example, adhesives of polymerization.

It is known that acrylic acid is obtained two-stage heterogeneously catalyzed partial oxidation in the gas phase propylene (see, for example, the document EP-A 990636, US-A 5198578, EP-A 1015410, EP-A 1484303, EP-A 1484308, EP-A 1484309 and US-A 2004/0242826).

Characteristic of the above-mentioned methods is that the acrylic acid thus obtained is not as such, but as a component of a mixture product gas, from which it must then be separated.

All relevant known methods of separation are common in General that, if necessary, after direct and/or indirect cooling of the mentioned mixture of the product gas contained in the mixture of the product gas of acrylic acid on the main stage of separation is translated in the condensed phase. This can be done, for example, by absorption in a suitable solvent (e.g. water, high-boiling organic solvents, aqueous solutions) and/or partial or substantially complete condensation (for example the EP, fractionation condensation) (see, for example, the above documents, the following documents EP-A 1388533, EP-A 1388532, DE-A 10235847, EP-A 792867, WO 98/01415, EP-A 1015411, EP-A 1015410, WO 99/50219, WO 00/53560, WO 02/09839, DE-A 10235847, WO 03/041833, DE-A 10223058, DE-A 10243625, DE-A 10336386, EP-A 854129, US-A 4317926, DE-A 19837520, DE-A 19606877, DE-A 190501325, DE-A 10247240, DE-A 19740253, EP-A 695736, EP-A 982287, EP-A 1041062, EP-A 117146, DE-A 4308087, DE-A 4335172, DE-A 4436243, DE-A 19924532, DE-A 10332758, DE-A 19924533). Department of acrylic acid may be also carried out as described in documents EP-A 982287, EP-A 982289, DE-A 10336386, DE-A 10115277, DE-A 19606877, DE-A 19740252, DE-A 19627847, EP-A 920408, EP-A 1068174, EP-A 1066239, EP-A 1066240, WO 00/53560, WO 00/53561, DE-A 10053086 and EP-A 982288. Suitable methods of separation are also described in documents WO 2004/063138, WO 2004/035514, DE-A 10243625 and DE-A 10235847 ways.

Further purification of the resulting within-described main compartment containing acrylic acid condensed phase can be carried out, for example, extraction, distillation, desorption and/or crystallization to the desired degree of purity acrylic acid. Further processing can be carried out, as described, for example, in documents WO 01/77056, WO 03/041832, WO 02/055469, WO 03/078378 and WO 03/041833.

A common feature of these methods of separation is that it usually remains a residual gas stream (cf. also the document EP-A 1180508) (typical in the head part are applied to the main office that contains EF the objective to separate the nozzle distillation columns), which contains mainly the components of a mixture of the product gas, the boiling point of which at normal pressure (1 bar) -30°C (i.e. hard condensed or easily volatile components). Components of the residual gas are not primarily used for partial oxidation reagents, i.e. molecular oxygen (usually used in excess relative to the stoichiometry of the reaction of partial oxidation, so it is advantageous to use the catalyst activity), and, if necessary, propylene, and primarily used in partial oxidation, an inert gas diluent such as nitrogen, noble gases, carbon dioxide and saturated hydrocarbons. Water vapor in the residual gas, depending on the applied method of separation can be contained only in traces, or up to 20 vol.%, or up to 25% vol. or more. The residual gas may contain small quantities and also acrylic acid and/or acrolein, which usually mainly separated as described.

The disadvantage of residual gas is that it can be recycled only in limited quantities in the reaction of partial oxidation. Almost complete recycling is impossible, because in such a direction circulating gas increased the level of components of the circulating gas. This is when the of Odilo to the flow of the reaction gas by the partial oxidation, where more would not be able to cope, and ultimately to their attenuation. Therefore, as a rule, half of the remaining recycle gas as the circulating gas oxidation in a partial oxidation process and the remaining number serves as the exhaust gas combustion (see, for example, EP-A 925272).

The above has inter alia the disadvantage that it reacted by partial oxidation, the remaining residual gas propylene disappears (separation of propylene from the residual gas and the subsequent separate recirculation of the separated propylene partial oxidation process due to the small fraction of the propylene unprofitable).

The negative effect of such a large primarily because as a feedstock to obtain acrylic acid is usually applied with a relatively high purity propylene (for example, "polymer grade" or "chemical grade" propylene; cf. the document DE-A 10131297), which usually passed the stage of separation of the other, due to the process of obtaining accompanying hydrocarbons, such as propane.

Among other things, so strive for high conversion of propylene in the first stage of the reaction (cf. WO 03/029177). The same is valid for the conversion of acrolein in the second stage of the reaction. This further because neprevyshenie in the second stage re the work acrolein, for example, in the framework of the separation of acrylic acid from a mixture of the product gas partial oxidation effect is negative (encourages undesirable, the tendency of acrylic acid to the polymerization (cf. for example DE-A 102004021764 and DE-A 102004021706)). to achieve the aforementioned high conversion in the prior art even recommended the subsequent reactor (cf. for example DE-A 102004021764 and DE-A 102004021706).

First of all, at the large enterprises of the two-stage partial oxidation of propylene to acrylic acid are committed in the first stage of the reaction for the conversion of propylene >of 99.5 mol.%, in order to completely abandon recirculation circulating gas oxidation in a partial oxidation process. This process has additionally the advantage that there is no need for the energy required for recirculation circulating gas oxidation (circulating gas oxidation before recycling should again be compacted by means of the turbocharger to pressure partial oxidation), and the cost of the compressor (for example, type 12 MNW firm Mannesmann DEMAG, DE).

High conversion usually requires highly active catalysts and/or high temperature partial oxidation. That, and the other a negative effect on the service life of the catalyst (compare DE-A 10351269 and DE-A 102004025445), primarily due to the fact that the mixture of the reaction is wow strip on each of the two stages of partial oxidation during its passage through the catalyst bed is held to the highest value, the so-called value of the hot spot.

For reasons of expediency, the temperature of the fixed catalyst layer and the effective temperature of the fixed catalyst layer are different from each other. In this case, the temperature of the fixed catalyst layer refers to the temperature of the fixed catalyst layer when carrying out the method of partial oxidation, however fictitious the absence of a chemical reaction (i.e. without the influence of the heat of reaction). Under the effective temperature of the fixed catalyst layer is understood in contrast, the actual temperature of the fixed catalyst layer with consideration of the heat of reaction of partial oxidation. If the temperature of the fixed catalyst layer along the fixed catalyst layer is not constant (for example, in the case of multiple temperature zones), the concept of the temperature of the fixed catalyst layer implies (numeric) the average temperature along a stationary catalyst layer. Needless to say, the temperature of the fixed catalyst layer along its length may be such that it is constant at a certain interval length, then abruptly changed and another segment length remains at this new value, etc. Then talk about having more than one temperature zone (or reaction is ONU) or more than one temperature zone (or reaction zone) fixed catalyst layer (filling a fixed catalyst layer). Implement these temperature zones (or reaction zone), the loaded catalyst reactors are referred to appropriately as "single" or "multi-zone reactors" (cf. for example WO 04/085369). With the temperature of the reaction gas mixture, the effective temperature of the fixed catalyst layer takes place in the direction of flow of the reaction gas mixture is hot points.

The possibility of reducing the temperature of a hot spot due to the fact that the method of partial oxidation is carried out at a reduced conversion of reagents can be used in conventional above-described partial oxidation of propylene to acrylic acid with significant disadvantages due to the same reason.

The objective of the invention is therefore the extension of the service life of the catalyst in obtaining acrylic acid by two-stage method heterogeneously catalyzed partial oxidation in the gas phase propylene.

The problem is solved using the method of reducing the temperature of the hot points of a fixed catalyst layer on the first stage partial oxidation in the process of obtaining acrylic acid by two-stage heterogeneously catalyzed partial oxidation in the gas phase propylene, in which:

A. in the first reaction stage propane in the presence of and/or with the exclusion of oxygen is and is subjected to a heterogeneously catalyzed dehydration, and get containing propane and propylene, and other than propane and propylene components, a mixture of 1 product gas (hereinafter: the product gas mixture 1),

b. from the educated to the first reaction stage product gas mixture 1, if necessary, make a partial quantity contained therein other than propane and propylene components, such as hydrogen and carbon monoxide, in other connections, other than propane and propylene and formed in the first reaction stage product gas mixture 1, if necessary, separate the partial quantity contained therein other than propane and propylene components, such as hydrogen, carbon monoxide and water vapor from the product gas mixture 1 receive a mixture of 1' the product gas (hereinafter: product gas mixture 1')containing propane and propylene, and other than oxygen, propane and propylene connection

C. the product gas mixture 1 or product gas mixture 1' as a component of the source of the reaction gas mixture 2 containing molecular oxygen, molecular nitrogen, propane and propylene in such a quantity that the molar ratio of O2:C3H6≥1 and the molar ratio of N2:O2is 2-6, loaded catalyst fixed bed 2, catalysts in which ka is este active masses have, at least, one containing the elements Mo, Fe and Bi oxide multimetallic, the second reaction stage is subjected to a heterogeneously catalyzed partial oxidation in the gas phase contained in the product gas mixture 1 or product gas mixture 1' propylene to acrolein, and get a mixture of 2 product gas (hereinafter: the product gas mixture 2),

d. the temperature leaving the second reaction stage product gas mixture 2, if necessary, reduce direct and/or indirect cooling, and to a product gas mixture 2, if necessary, add molecular oxygen and/or inert gas,

that is, after that as a starting reaction gas mixture 3, which contains molecular oxygen, molecular nitrogen, propane, acrolein, when this molar ratio is O2:C3H4O≥0,5, loaded catalyst fixed bed 3, the catalysts whose active mass have, at least, one containing the elements Mo and V oxide multimetallic, the third reaction stage is subjected to a heterogeneously catalyzed partial oxidation in the gas phase contained in the source of the reaction gas mixture 3 acrolein in acrylic acid, and receive a mixture of 3 product gas (hereinafter: the product gas mixture 3),

f. from the product gas mixture 3 in section a is sustained fashion zone And separating acrylic acid, which if necessary cleaned, and at least contained in the product gas mixture 3 unreacted propane and propylene return each of at least 80 mol.%, in terms of contained in the product gas mixture 3 the amount of each, for at least the first of the three reaction stages, characterized in that:

i. the second reaction stage is carried out until a conversion UPpropylene, which is ≤99 mol.%, in terms of a one-time pass through it, and

ii. the third reaction stage is carried out until a conversion UAacrolein equal to ≥96 mol.%, in terms of a one-time pass through it, the method includes at least one separate selection for other than propane and propene components, which contains propane and propene in the amount of <5%vol.

Change in source of raw materials to the generally much more favorable relative cost of propane and related opportunity, at least one, preferable a separate economic output other than propane and propene) components while simultaneously possible quantitative returning unreacted propane from the partial oxidation in the source propane, opening potential is reduced conversion of propylene in the first reaction stage, followed by further without dopolnitelbnogo associated with propane possible total recirculation of propylene in a General way, still not observed.

According to the invention is favorable to carry out the method according to the invention so that:

better UP≤a 99.0 mol.% and UA≥96 mol.%, or

better UP≤to 98.5 mol.% and UA≥96 mol.%, or

better UP≤98,0 mol.% and UA≥96 mol.%, or

better UP≤a 97.5 mol.% and UA≥96 mol.%, or

better UP≤97,0 mol.% and UA≥96 mol.%, or

better UP≤96,5 mol.% and UA≥96 mol.%, or

better UP≤96,0 mol.% and UA≥96 mol.%, or

better UP≤95,5 mol.% and UA≥96 mol.%, or

better UP≤95,0 mol.% and UA≥96 mol.%, or

better UP≤94,5 mol.% and UA≥96 mol.%, or

better UP≤94,0 mol.% and UA≥96 mol.%, or

better UP≤93,5 mol.% and UA≥96 mol.%, or

better UP≤93,0 mol.% and UA≥96 mol.%, or

better UP≤92,0 mol.% and UA≥96 mol.%, or

better UP≤91,0 mol.% and UA≥96 mol.%, or

better UP≤90,0 mol.% and UA≥96 mol.%, or

better UP≤85,0 mol.% and UA≥96 mol.%, or

better UP≤80,0 mol.% and UA≥96 mol.%, or

better UP≤75,0 mol.% and UA≥96 mol.%.

As a rule, UPall of the above values is ≥ 50 mol.%, preferably ≥ 60 mol.%, particularly preferably ≥ 70 mol.%.

Needless to say, UPmay be ≥ 75 mol.%, or ≥ 80 mol.%, or ≥ 85 mol.%, or≥ 90 mol.%. This means that each range according to the invention for UPis the possible combination of the above lower bounds for UPwith the above higher limit for UP.

Further according to the invention, preferably, when each of the above value UPUA-combination UA≥to 96.5 mol.%, better ≥ 97 mol.%, better ≥ 97,5 mol.%, better ≥ 98 mol.%, better ≥ 98,5 mol.%, better ≥ 99 mol.%, best GE; 99.5 mol.%, better ≥ to 99.6 mol.%, better ≥ of 99.7 mol.%, better ≥ 99,8 mol.%, better ≥ 99,9 mol.%, better ≥ 99.91 per mol.%, better ≥ 99,92 mol.%, better ≥ 99,93 mol.%, better ≥ 99,94 mol.%, better ≥ 99,95 mol.%, better ≥ of 99.96 mol.%, better ≥ of 99.97 mol.%, better ≥ of 99.98 mol.%, better ≥ 99,99 mol.%.

Above the highest value achievable, for example, when the third reaction stage includes at least one additional reactor according to DE-a 102004021764, respectively, DE-A 1020040217063. Alternative options apply the method described in these documents of the prior art.

As a rule, UA<100 mole%, accordingly, not more than 99,995 mol.%. Often UA≤99,99, or ≤ of 99.98, or ≤ 99,96, or ≤ 99,95 mol.%. This means that the possible range according to the invention for UAis each possible combination of the above lower bounds for UAe above high boundary for UA. Since UPand UAthe ri method according to the invention can be installed independently from each other, also the range for UPcan be freely combined with ranges for UA. Preferably, the preferred range for UPcombined with the preferred range for UA.

According to the invention is particularly preferably a value for UPfrom 80 to 98 mol.%, while value for UAfrom a 99.0 to 99.9 mol.%. Another combination according to the invention is UPfrom 90 to 98 mol.%, while value for UAfrom a 99.0 to 99.9 mol.% or more, respectively, of 99.3 to 99.6 mol.%.

Further, for the method according to the invention is favorable, regardless of UAand UPg, if after the separation of acrylic acid from product gas mixture 3 in the separation zone And contained in the product gas mixture 3 unreacted propane and propylene is recycled, at least in the first of the three reaction stages, at least every one to 85 mol.%, better at least every 90 mol.%, better at least every 92 mol.%, better at least every 94 mol.%, better at least every 95 mol.%, better at least everyone on the 95.5 mol.%, better at least every 96 mol.%, better at least on each of 96.5 mol.%, better at least every one to 97 mol.%, better at least on each of 97.5 mol.%, better at least every 98 mol.%, better at least, is the very 98.5 mol.%, better at least every one to 99 mol.%, better at least every 99.5 mol.%, better at least on each of 99.75 or at least about 99.9 mol.% and better quantified (each time with the terms contained in the product gas mixture 3 number of propane, respectively, propylene). According to the invention a so-called recirculation of propane and propylene is carried out exclusively on the first stage. It can be partially (for example, up to 50 wt.%, or up to 30 wt.%, or up to 20 wt.%, or up to 10 wt.%, or up to 5 wt.% or less) on the second and/or third reaction stage.

In the case of the second reaction stage, the place of supply may be located between the first and second reaction stages With3-the Department (for example, as gas distillation light ends).

According to the invention is suitable manner above the recirculation of propane and propylene is carried out in combination, i.e. are in the same recirculation gas. Below such recirculation gases called With3-circulation gas.

In the simplest case when C3-circulation gas we can talk about the oxidation of the circulating gas. This means that in the separating zone And contained in the product gas mixture 3 acrylic acid translated as the target product, for example, absorption or condenser measures of g is sobrannogo States in the condensed phase. As agents of absorption suitable for this, for example, water and/or organic solvents (in particular, under normal conditions (25°C, 1 bar) higher boiling than acrylic acid, hydrophobic organic solvents) (in principle branch (condensation) may be carried out, as described in documents EP-A 117146, DE-A 4308087, DE-A 4335172, DE-A 4436243, DE-A 19924533, EP-A 982287, EP-A 982289, DE-A 19924532, DE-A 10115277 DE-A 19606877, DE-A 19740252, DE-A 19627847, DE-A 10053086 and EP-A 982288, preferably, as shown in figure 7 of document WO 0196271, as well as in DE-A 102004032129 and its equivalents). Within this "condensation" of acrylic acid remains, as already described above, is usually not a challenge in condensed phase residual gas (oxidizing circulating gas), which (compared to the acrylic acid) includes a relatively hard "condensed" components of the product gas mixture 3. They are, as already mentioned, the components, the boiling point of which at normal pressure (1 bar) -30°C (their total share in an oxidizing residual gas is, as a rule, 70%, often 80% vol. and more often 90%).

The product gas mixture 3 with the method according to the invention is essentially composed of the target product of acrylic acid, unreacted molecular oxygen, propane, unreacted propylene, molecular nitrogen, resulting in image quality is as a by-product and/or applied as a gas-solvent hydrogen, formed as a side product and/or applied as a gas-thinner oxides of carbon, residual quantities of acrolein, and small amounts of other lower aldehydes, lower alkenylboronic acids (e.g. acetic acid, formic acid and propionic acid)and maleic anhydride, benzaldehyde, aromatic carboxylic acids and aromatic anhydrides of carboxylic acids (e.g., anhydride talavou acid and benzoic acid), and, if necessary, other hydrocarbons and other inert gaseous diluents.

In accordance with the above to oxidative circulating gas according to the invention are primarily unreacted propane, unreacted propylene, and, as a rule, O2and an inert gas diluent such as, for example, methane, ethane, and N2, CO2noble gases (Ne, Ar etc.), CO, and a small amount of acrylic acid and acrolein, and, if necessary, acetic acid, formaldehyde and formic acid, and ethylene. The water vapor content can be up to 25 vol.%, often up to 20 vol.%, or only up to 10 vol.%, however, often below 10% vol. or below 5 vol.%. Other lower aldehydes and alcancarao acid may also be contained in small amounts.

This means that, as a rule, slitely circulating gas is used for both reaction stages inert gaseous diluents, and also produced as a by-product or added as the diluent gas of water vapor and educated unwanted full oxidation of carbon oxides.

According to the invention the oxidation of the circulating gas as such (and with it contained in the propane and propylene) can be recycled to the first reaction stage (reaction stage 1). Needless to say, it also contains propane and propylene may be separated from the other components and, as such or in the presence of a small number of such components be recycled to the first reaction stage. In the latter case, this is the first release for other than propane and propylene components of the method according to the invention.

This separation of propane and propylene can be carried out, for example, by absorption with subsequent desorption and/or Stripping (and re-use of an agent absorption) in the high-boiling hydrophobic organic solvent (for example, tetradecane). Further features of the Department are adsorption, distillation, membrane method and parallel condensation. Preferably these methods of separation performed at high pressure.

When applying the dehydrogenation catalysts which are sensitive to oxygen or to contain Asim oxygen compounds before recycling propane and propylene these compounds are separated from them. This separation of oxygen may make sense when you want to prevent the combustion of propane and/or propylene in the return to the stage dehydrogenation. The dehydrogenation catalysts in the document DE-A 19937107 not sensitive to oxygenates (in particular those listed in examples 1 to 4 of this document DE-A).

Another possibility branch is fractionated in distillation. Preferably fractionated distillation is carried out at low temperatures. The applied pressure may be, for example, 10 to 100 bar. The distillation column can be Packed columns, plate columns or columns with nozzles. As columns with nozzles suitable such which have a double nozzle cap nozzle and valve plates. Reflux can be, for example, from 1 to 10. Other features of the Department is formed, for example, extraction under pressure, adsorption with changing pressure, flushing under pressure, partial condensation and extraction under pressure.

If a3-the circulation gas before it is recirculated to the first reaction stage still contains carbon monoxide, it can advance to catalytically combusted before recirculation in CO2. The resulting CO2can the t can then be relatively easily separated by washing the primary fluid.

Of course, you can do so that only part of the circulating oxidative gas unaltered, in its composition recycle to the first stage and only the remaining part is separated in a mixture (combination) propane and propylene and also recycle to the first stage (as already mentioned, can all described recirculation propane/propylene partially takes place on the second and/or third reaction stage).

In the framework of the separation of propane and propylene fractionated by distillation oxidative circulating gas separation line can be installed so that the lifting part of the distillation column mainly separated all the components and disposed in the upper part of the column, boiling point which is lower than the boiling point of propylene. These components are in the first line of the oxides of carbon (CO and CO2and unreacted oxygen and ethylene, and methane, ethane and N2. In the lower part of the column can be separated more low-boiling than propylene and propane components.

If the first reaction stage of the method according to the invention is applied heterogeneously catalyzed oxidisation propane, issue other than propane and propylene side components can always be carried out when, as described in the documents DE-A 19837520, DE-A 19837517, DE-A 19837519 and DE-A 1837518, is the Department of molecular nitrogen.

The above-described oxidative circulating gas forms (in terms of the number of propane and propylene) principal amount (usually at least 80 wt.%, accordingly, at least 90 wt.%, or, at least 95 wt.% or more) all With3-the circulation of gases method according to the invention, therefore, derived by division side components containing propane circulating gas flows are also called principal3-circulation gas.

In particular, when the condensation of the acrylic acid absorption occurs by means of an organic solvent in the separation zone And, as a rule, is formed, at least one second containing unreacted propane, and residual unreacted propylene gas, which according to the invention is treated as a3-the circulation gas. In terms of contained propane and propylene his number in comparison with the principal3-circulation gas in the normal case is much lower. This is due to the fact that the resulting absorbate along with acrylic acid in an amount to be determined accepts propane and propylene. In a further passage extraction, distillation, crystalline and/or desorption separated the I of acrylic acid from the condensed phase, accordingly, from absorbate, this unreacted propane and propylene according to the invention is recovered as a component, at least one further gas phase and recycle as further3-circulating gas. Before recycling, as described for main3-circulating gas, as another possible release side components can be produced compartment side components (regardless of whether made this compartment side components or not, for these recycled With3-the circulation of gases applied the concept side With3-the circulation gas).

Recycling side With3-the circulation of gases may occur alone or in a mixture with the main3-circulation gas. For the latter applies the concept in common With the3-the circulation gas. Side3-circulating gases may be free from oxygen or also contain oxygen. The latter takes place when they are produced by steaming through the air or in the upper part of the wash air as an inhibitor of polymerization of the distillation column. With the advantage side With3-circulating gases can be fed due to their limit and also directly to the output is MESI 2 reaction gas (preferably) and/or output reaction gas mixture 3.

Preferably according to the invention recirculation With3-the circulation of the gases may be carried out in the first reaction stage in the initial mixture 1 reaction gas, which is used to load the stage and contains required for the method according to the invention fresh propane. It may be also carried out along the conversion of the dehydrogenation in reaction stage 1, as recommended in the document DE-A 102004032129.

Under the fresh propane in the present description refers to propane, which has not participated in any chemical reaction. As a rule, it is crude propane (which fulfills the specifications according to the documents DE-A 10246119 and DE-A 10245585), which in small quantities also contains other than propane components.

Original mix 2 reaction gas for the partial oxidation of propylene to acrolein does this description recommended in the documents DE-A 10246119 and DE-A 10245585 specification.

Unlike passing exothermically, homogeneous or heterogeneous catalyzed oxidisation, which is present in oxygen and in which the intermediate no longer produces free hydrogen (open from subject to dehydrogenation of propane hydrogen comes off immediately as water (H2O)), respectively, is not proved, under heterogeneously catalyzed Degi what risovaniem should be same ("normal") dehydrogenation, thermal effect which unlike oxidisation is endothermic (as a subsequent step in the heterogeneously catalyzed dehydrogenation may be exothermic combustion of hydrogen) and in which at least the intermediate formed free molecular hydrogen. This requires, as a rule, other reaction conditions, and other catalysts than for oxidisation.

Under load catalytic reaction stage catalyst layer with the output of the reaction gas mixture in the present description refers to the number of the source of the reaction gas mixture in normal litres (IO; the volume in liters, which would be an appropriate source of the reaction gas mixture under normal conditions (0°C, 1 bar)), in which h is passed through one liter of fixed catalyst layer.

The load can also be calculated on the composition of the reaction of the source gas mixture. Then the amount of this component in the nl/l·h, in which h is passed through the catalyst fixed bed (clean backfill of intermaterial are not classified as fixed catalyst layer).

As the inert gas in the present description should be understood component of the reaction gas, which under the reaction conditions mainly behaves as an inert and, considering each inert the first component by itself, more than 95 mol.%, preferably more than 99 mol.% remains chemically unchanged

In principle, the content of propylene source of the reaction gas mixture 2 in the aspect of satisfactory distribution of space and time is 4 vol.%. The method according to the invention, however, especially advantageous when the content of propylene in the source of the reaction gas mixture 2 is ≥7%vol.

In the normal case the above propylene content of 15 vol.%. According to the invention is preferably a propylene content in the source of the reaction gas mixture 2 is from 7 to 12 vol.%, especially preferably from 7 to 11% vol. and even more preferably from 7 to 10 vol.%, accordingly, from 7 to 9 vol.%. The content of propylene according to the invention the source of the reaction gas mixture 2 is about 8 vol.%.

Further according to the invention is preferred that the molar ratio of V1contained in the source of the reaction gas mixture 2 propane contained in the source of the reaction gas mixture 2 to propylene is from 1 to 4. Preferably V1=1 to 3.5, particularly preferably 1 to 3.0 or 1 to 2.5, and very preferably V1=1.5 to 2.2.

In addition, for the method according to the invention is of particular advantage that the molar ratio contained in the source the second reaction gas mixture 2 molar nitrogen contained in the source of the reaction gas mixture 2 molecular oxygen is 2 to 6, preferably from 3 to 4.5, particularly preferably from 3.5 to 4.5 and more preferably from 3.5 to 4, respectively, of 3.73.

Further, for the method according to the invention, preferably, if the molar ratio of V3contained in the source of the reaction gas mixture 2 molecular oxygen contained in the source of the reaction gas mixture 2 to propylene is from 1.3 to 2.4, preferably from 1.4 to 2.2, particularly preferably from 1.4 to 2.1 and still more preferably from 1.5 to 2.1, respectively, from 1.7 to 2.1 or 1.9.

A possible source of the reaction mixture 2 contains:

6 to 9 vol.% propylene,

8 to 18% vol. molecular oxygen,

6 to 30 vol.% propane and

32 to 72% molecular nitrogen

with

V1=1 to 4

V2=2 to 6 and

V3=1.3 to 2.4.

The preferred source of the reaction gas mixture 2 contains:

7 to 9 vol.% propylene,

9.8 to 16% vol. molecular oxygen,

9 to 25 vol.% propane and

35 to 65% by molecular nitrogen

with

V1=1 to 3.5,

V2=3 to 4.5 and

V3=1.4 to 2.2.

Particularly preferred source of the reaction gas mixture 2 contains:

7 to 9 vol.% propylene,

9.8 to 15% vol. molecular oxygen,

10.5 to 20% vol. propane and

40 to 60 vol.% molecular nitrogen

with

V1=1.5 to 2.5,

V2=3.5 to 4.5 and

V3=1,4 to 2.14.

More FAV is citicolina source gas, the reaction mixture 2 contains:

7 to 8% vol. propylene,

11.9 to 15,5% vol. molecular oxygen,

11.9 to 15,5% vol. propane and

50 to 60 vol.% molecular nitrogen

with

V1=of 1.7 to 2.1,

V2=3.5 to 4.5 and

V3=of 1.7 to 2.1.

In principle, the content of acrolein source in the reaction gas mixture 3 is when the aspect satisfactory output in space and time 3.%.

The method according to the invention is then particularly preferred when the content acrolein in the source of the reaction gas mixture 3 is 4, or ≥5 or ≥5,5 or ≥6 vol.%. In the normal case the above content acrolein is 15 vol.%. Preferred according to the invention the content of acrolein in the reaction gas mixture 3 from 6 to 11 vol.%, especially preferably from 6 to 10 vol.% and even more preferably from 6 to 9, respectively, from 6 to 8 vol.%. Instead of the number 6 can also stand in the above boundaries figure of 5.5. The preferred content of acrolein according to the invention in the reaction gas mixture 3 is about 7%.

Further, for the method according to the invention is particularly mainly that the molar ratio of V4contained in the source of the reaction gas mixture 3 oxygen contained in the source of the reaction gas mixture 3 acrolein is ≥0.5 and ≤2, with a preference ≥1 and ≤1,75, particularly preferably ≥1 and ≤1.5 and E. the e is more preferably ≥1 and ≤1,25.

Advanced mainly for the method according to the invention that the molar ratio of V5contained in the source of the reaction gas mixture of propane contained in it acrolein is from 1 to 4, with the advantage of from 1.5 to 3.5, particularly preferably from 1.5 to 3 and more preferably of 1.5, respectively, from 2 to 2.5.

A possible source of the reaction gas mixture 3 according to the invention contain:

4.5 to 8% vol. acrolein,

2,25, respectively, 4,5 to 9% vol. molecular oxygen,

6 to 30 vol.% propane,

32 to 72% molecular nitrogen and

5 to 15 vol.% water vapour.

The preferred source of the reaction gas mixture 3 according to the invention contain:

5.5 to 8% vol. acrolein,

2,75, respectively, 5,5 to 9% vol. molecular oxygen,

10 to 25 vol.% propane,

40 to 70 vol.% molecular nitrogen and

5 to 15 vol.% water vapour.

Particularly preferred source of the reaction gas mixture 3 according to the invention contain:

6 to 8 vol.% acrolein,

3, respectively, 6 to 9 vol.% molecular oxygen,

10 to 20 vol.% propane,

50 to 65% by molecular nitrogen and

7 to 13 vol.% water vapour.

Favorable according to the invention is that a possible source of the reaction gas mixture 2 and the possible source of the reaction gas mixture 3, or predpochtite is supplemented flax source of the reaction gas mixture 2 and the preferred source of the reaction gas mixture 3, or particularly preferred source gas mixture 2, or particularly preferred source of the reaction gas mixture 3 with the method according to the invention are used in combination.

Generally, as the source of the reaction gas mixture 2 and the source of the reaction gas mixture 3 contain in addition to the mentioned components ≤ 10 vol.%, preferably ≤ 8 vol.%, particularly preferably ≤ 5% vol. and even more preferably ≤ 3% vol. the other components.

The content in the reaction gas mixture 2 and the reaction gas mixture 3 methane and/or ethane, as a rule, is ≤ 8%, in most cases ≤ 5% vol. and usually ≤ 3 vol.%, accordingly, ≤ 2 vol.%. Often, however, the advantage is (both are basically inert and has favorable heat conductivity) ≥ 0,5%vol.

Particularly preferably the total content of oxides of carbon (CO2WITH) the source of the reaction gas mixture 2 and the source of the reaction gas mixture 3 with the method according to the invention is ≤ 5 vol.%, particularly preferably ≤ 3 vol.%, accordingly, 2%vol.

Accordingly, the reaction gas mixture 2 contains the advantage of ≤ 5% vol. water, preferably ≤ 3% vol. water, particularly preferably ≤ 2% vol. water and, as a rule, ≥ 0,5% vol. water.

Load as a fixed catalyst layer 2, the AK and fixed catalyst layer 3 corresponding to the source of the reaction gas mixture according to the invention is from 1500 to 4000, accordingly, 6000 nl/l·h or more.

Load as a fixed catalyst layer 2 and the fixed catalyst layer 3 corresponding reagents (propylene, respectively, acrolein) is usually ≥ 70 nl/l·h, mainly ≥ 90 nl/l·h or ≥ 120 nl/l·h, particularly preferably ≥ 140 nl/l·h and even more preferably ≥ 160 nl/l·h usually referred to load the reagent is ≤ 600 nl/l·h, more preferably ≤ 300 nl/l·h, frequently ≤ 250 nl/l·H.

As for the first reaction stage, and a third pressure of the reaction is usually from 0.5 to 3 bar, and the interval from 1 to 3 bar preferred. The temperature of the fixed catalyst layer 2 to the second reaction stage, usually ranging from 300 to 400°C. the temperature of the fixed catalyst layer 3 in the third reaction stage, usually ranging from 200 to 350°C.

In that case, if the first reaction stage we are talking about oxidisation propane, it can be as homogeneous and/or heterogeneous catalyzed acidication propane to propylene with molecular oxygen in the gas phase. As the source of molecular oxygen can be air, pure molecular oxygen or enriched with molecular oxygen. As an alternative source kislorodnogo to serve nitric oxide, such as NO2N2O4etc.

If the first stage performed as homogeneous oxidisation, it can be done, in principle, thus, as described in documents US-A 3798283, CN-A 1105352, publication, Applied Catalysis, 70(2)1991, S.175-187, Catalysis Today 13, 1992, S.673-678, and in the application DE-A 19622331. A suitable source of oxygen may be air. The temperature of the homogeneous oxidisation expediently chosen in the range from 300 to 700°C., preferably in the range from 400 to 600°C., particularly preferably in the range from 400 to 500°C. the Operating pressure may be from 0.5 to 100 bar, in particular from 1 to 10 bar. The residence time is generally 0.1, respectively, from 0.5 to 20 seconds, preferably about 0.1, respectively, from 0.5 to 5 seconds.

As the reactor can be used, for example, a tubular reactor or tube and shell reactor, for example a tubular reactor with countercurrent to the flue gas as a coolant and shell-and-tube reactor with salt as a coolant. The ratio of propane to oxygen in the corresponding source of the reaction gas mixture 1 is preferably from 0.5:1 to 40:1, especially between 1:1 and 6:1 and even more preferably between 2:1 and 5:1. The source of the reaction gas mixture 1 may include preferably inert (under inert components, you should understand how it is mentioned, preferably such that under the conditions of this reaction are transformed to less than 5 mol.%, preferably less than 3 mol.% and especially preferably less than 1 mol.%, especially preferably not turn) components, such as water, carbon dioxide, carbon monoxide, nitrogen, noble gases, other hydrocarbons (e.g. containing crude propane side components), and/or propylene, and here we can talk about recycled (circulating gas) components.

If the propane dehydrogenation perform as heterogeneously catalyzed oxidisation, this principle is carried out, as described, for example, in the publications US-A 4788371, CN-A 1073893, Catalysis Letters 23 (1994), 103-106, W.Zhang, Gaodeng Xuexiao Huaxue Xuebao, 14 (1993) 566, Z.Huang, Shiyou Huagong, 21 (1992) 592, WO 97/36849, DE-A 19753817, US-A 3862256, US-A 3887631, DE-A 19530454, US-A 4341664, J. of Catalysis 167, 560-569 (1997), J. of Catalysis 167, 550-559 (1997), Topics in Catalysis 3 (1996) 265-275, US-A 5086032, Catalysis Letters 10 (1991), 181-192, Ind. Eng. Chem. Res. 1996, 35, 14-18, US-A 4255284, Applied Catalysis A: General, 100 (1993), 111-130, J. of Catalysis 148, 56-67 (1994), V. Cortés Corberán and S.Vic Bellyn (Ed.), New Developments in Selective Oxidation II, 1994, Elsevier Science B.V., S.305-313, 3rdWorld Congress on Oxidation Catalysis, R.K.Grasselli, S.T.Oyama, A.M.Gaffney and J.E.Lyons (Ed.), 1997, Elsevier Science B.V., S.375ff or in DE-A 19837520, DE-A 19837517, DE-A 19837519 and DE-A 19837518. At the same time as the oxygen source may be air. Often as the source of oxygen is at least 90 mol.% from molekulyarnoj is oxygen, often, at least 95 mol.% of molecular oxygen.

Suitable for heterogeneously catalyzed oxidisation catalysts are not subject to any special restrictions. Suitable all well-known expert in the field of catalysts oxidisation, which are able to oxidize propane into propylene. In particular, can be used all mentioned in the above publications catalysts oxidisation. Suitable catalysts are, for example, catalysts oxidisation, which include MoVNb-oxides or pyrophosphate of vanadia, if necessary with the promoter. Examples for suitable catalyst oxidisation is a catalyst that contains a metal oxide with Mo, V, Te, O and X as an essential component, and X represents at least one element selected from the group comprising niobium, tantalum, tungsten, titanium, aluminum, zirconium, chromium, manganese, gallium, iron, ruthenium, cobalt, rhodium, Nickel, palladium, platinum, antimony, bismuth, boron, indium, silicon, lanthanum, sodium, lithium, potassium, magnesium, silver, gold and cerium (cf. for this and also the documents EP-A 938463 and EP-A 167109). Further particularly suitable catalysts for oxidisation are active mass on the oxide multimetallic, respectively, catalysts And from the document DE-A 1975381 and catalysts from the document DE-A 19838312, and mentioned in the first document as the preferred active mass on the oxide multimetallic, respectively, the catalysts are particularly favorable. This means that as the active mass to oxidisation suitable, in particular, the active mass on the oxide multimetallic the following General formula:

M1aMo1-bM2bOx,

and

M1=Co, Ni, Mg, Zn, Mn and/or Cu,

M2=W, V, Te, Nb, P, Cr, Fe, Sb, Ce, Sn and/or La,

a=0.5 to 1.5,

b=0-0,5,

and

x = the number that is determined by the valence and amount of non-oxygen elements in the formula.

In principle suitable active mass of the above General formula can be obtained in a simple way due to the fact that from suitable sources of their elemental constituents receive thin, drawn up in accordance with their stereometry dry mixture and this mixture calicivirus at temperatures from 450 to 1000°C. as sources for the elementary components of the General formula are suitable such compounds, which are oxides and/or those compounds which can be converted into oxides by heating, at least in the presence of oxygen. This involves, first of all, halides, nitrate, formate, oxalates, citrates, acetates, carbonates, amine complex salts, manievich salts and/or hydroxides. Especially good homogeneous mixture of the source compounds for production of the active mass on the oxide multimetallic may be in dry form, for example as a fine powder or in a wet form, for example, with water as solvent. Rezultiruja mass on the oxide multimetallic can be used for oxidation as in powder form, and as catalysts, molded into a specific geometric shape, and the shaping may be effected before or after the final calcination. They can be used as solid catalysts. Shaping the powdered active material, respectively, the mass of the catalyst precursor, may, however, be also applied to preformed catalyst carriers. As the material of the carrier may be applied in conventional, porous or nonporous aluminum oxide, silicon dioxide, thorium dioxide, zirconium dioxide, silicon carbide or silicates, and the body of the carrier can be formed with uniform or nonuniform (correct or incorrect on the form).

For heterogeneously catalyzed oxidisation propane, the reaction temperature preferably lies in the range from 200 to 600°C., in particular in the range from 250 to 500°C., even more preferably in the range is from 350 to 440°C. Working pressure preferably lies in the range from 0.5 to 10 bar, in particular from 1 to 10 bar, more preferably from 1 to 5 bar. Working pressure above 1 bar, for example from 1.5 to 10 bar, has proved particularly preferred. Typically heterogeneously catalyzed oxidisation propane is carried out on the fixed catalyst layer. Last expedient manner is poured into the tube shell-and-tube reactor as described, for example, in EP-A-0700893 and in EP-A-0700714, and cited them in the literature. The average residence time of the reaction mixture 1 in the catalyst bed is suitable from 0.5 to 20 seconds. The ratio of propane to oxygen varies with the desired conversion and selectivity of the catalyst. It is expedient manner from 0.5:1 to 40:1, in particular from 1:1 to 6:1, more preferably from 2:1 to 5:1. Typically, the propylene selectivity decreases with increasing conversion of propane. Preferably the reaction of propane to propylene is carried out in such a way that is relatively low propane conversion at high selectivity to propylene. Particularly preferably, the conversion of propane is in the range from 5 to 40 mol.%, often in the range of from 10 to 30 mol.%. The term "conversion of propane" means a share summed propane (the amount of crude propane and terasawa recycled With 3-circulating propane gas) in a single pass. Typically, the selectivity of the formation of propylene is from 50 to 98 mol.%, more preferably, from 80 to 98 mol.%, moreover, the term "selectivity" means moles of propylene that get in mol converted propane, expressed in molar percentage amounts.

Usually applied during the oxidative dehydrogenation of propane initial mixture contains from 5 to 95 mol.% propane (based on 100 mol.% the original mix). Along with propane and oxygen the initial mixture for the heterogeneously catalyzed oxidisation may include other features, inert components, such as carbon dioxide, carbon monoxide, nitrogen, noble gases, other hydrocarbons, such as contained in the crude propane side components and/or propylene. Heterogeneously catalyzed oxidisation may be also carried out in the presence of diluents, for example water vapor.

For carrying out homogeneous oxidisation or heterogeneously catalyzed oxidisation propane can be used any combination of reactors, which is known to the specialist. For example, oxidisation can be conducted in a single reactor or in a cascade of two or more reactors, between which, if necessary, may be given keys the location. There is a possibility of homogeneous and heterogeneous catalyzed oxidisation be implemented in combination with each other.

As possible components of the product gas mixture 1 can contain, for example, the following: propylene, propane, carbon dioxide, carbon monoxide, water, nitrogen, oxygen, ethane, Aten, methane, acrolein, acrylic acid, ethylene oxide, butane (for example, n-butane or ISO-butane), acetic acid, formaldehyde, formic acid, propionoxy and butenes (e.g., butene-1). A typical image obtained by oxidisation propane according to the invention the product gas mixture contains 5 to 10 mol.% propylene, 0.1 to 2 mol.% carbon monoxide, 1 to 3 mol.% carbon dioxide 4 to 10 mol.% water, 0 to 1 mol.% nitrogen, 0.1 to 0.5 mol.% acrolein, 0 to 1 mol.% of acrylic acid, 0.05 to 0.2 mol.% acetic acid is 0.01 to 0.05 mol.% formaldehyde, 1 to 5 mol.% oxygen, 0.1 to 1.0 mol.% other above-mentioned components, as well as the remainder mainly propane, in each case based on 100 mol.% the product gas mixture.

According to the invention preferably it is in the first reaction stage on conventional heterogeneously catalyzed partial dehydrogenation of propane.

In principle can be any known heterogeneously catalyzed partial dehydrogenation reaction of propane, as described, for example, in public, the operations WO 03/076370, WO 01/96271, EP-A 117146, WO 03/011804, US-A 3161670, WO 01/96270, DE-A 3313573, DE-A 10245585, DE-A 10316039, as well as in the application DE-A 102004032129. Also suitable are all known from the prior art dehydrogenation catalysts. Preferably, the dehydrogenation is carried out in a fixed catalyst layer.

The dehydrogenation catalysts can be roughly divided into two groups. Namely, one that is oxidizing nature (for example, chromium oxide and/or aluminum oxide), and one that consists of at least one, usually precipitated as a rule, oxidizing media, as a rule, relatively noble metal (e.g. platinum). Among other things, this can be used as all dehydrogenation catalysts which are recommended in the documents DE-A 10219879, WO 01/96270, EP-A 731077, DE-A 10211275, DE-A 10131297, WO 99/46039, US-A 4788371, EP-A-0705136, WO 99/29420, US-A 4220091, US-A 5430220, US-A 5877369, EP-A 0117146, DE-A 19937196, DE-A 19937105, and also DE-A 19937107, and the catalyst according to example 4 of document DE-A 10219879. In particular, can be used as catalysts according to example 1, example 2, example 3 and example 4 of the document DE-A 19937107 and the catalyst according to example 4 of the document DE-A 10219879, and the catalyst WO 02/51547, WO 02/51540 and DE-A 102005002127.

When it comes to the dehydrogenation catalysts which contain 10 to 99.9 wt.% Zirconia, 0 to 60 wt.% aluminum oxide, silicon dioxide and/or diox is Yes titanium and 0.1 to 10 wt.%, at least one element of the first or second main group element of the third side of the group, the eighth element side group of the Periodic system of the elements, lanthanum and/or tin, with the proviso that the sum of the weight percent amounts to 100 wt.%.

Especially suitable and used in the example of this description, the dehydrogenation catalyst.

In General, the dehydrogenation catalysts we can talk about catalyst bundles (diameter typically from 1 to 10 mm, preferably 1.5 to 5 mm, a length of typically from 1 to 20 mm, preferably from 3 to 10 mm), tablets (preferably the same size as that for the catalyst binders) and/or catalyst rings (external diameter and length of each time 2 to 30 mm or 10 mm, wall thickness expediently from 1 to 10 mm, or 5 mm, or 3 mm).

Generally, the dehydrogenation catalysts (particularly those used in the present description, as recommended in the document DE-A 19937107 (particularly those mentioned as examples of catalysts of this document DE-A)) are made so that they can catalyze both the propane dehydrogenation and combustion of molecular hydrogen. The hydrogen burning takes place in comparison with propane dehydrogenation in the case of the competitive situation on the catalysts is much faster.

For carrying out heterogeneously catalyzed dehydrin is of propane are suitable in principle, all known from the prior art reactor types and variants of the method. Description of these options method contain all cited with respect to the usual dehydrogenation and related catalysts publishing technology.

Typical partial heterogeneously catalyzed dehydrogenation of propane is that it is endogenous. This means that required to adjust the reaction heat (energy) must be wired to the source of the reaction gas mixture 1 or before and/or during the heterogeneously catalyzed dehydrogenation. If necessary, the reaction gas mixture 1 has the desired heat to dissipate itself.

Next for the heterogeneously catalyzed dehydrogenation of propane due to the high desired reaction temperature is typically that in small amounts are formed of the low-boiling organic compounds to carbon, which forms on the surface of the catalyst and consequently inactivate it. To reduce these negative accompanying phenomena, subject to submission for heterogeneously catalyzed dehydrogenation at elevated temperature through the surface of the catalyst containing propane reaction gas mixture 1 may be diluted with water vapor. Deposited carbon under these conditions is removed partially or completely on the principle of gasification of carbon.

Another possibility of removal osadivshih carbon is soedinenii is the dehydrogenation catalyst from time to time (when you need every day or every hour) rinse at high temperature oxygen-containing gas (an expedient manner in the absence of hydrocarbons) and how would burn usageprice carbon. Another suppression of deposition of carbon is also possible due to the fact that to be heterogeneously catalyzed the dehydrogenation of propane before it at a high temperature is sent over a dehydrogenation catalyst, add molecular hydrogen. High conversion of the dehydrogenation cause, as a rule, short periods of regenerating.

Needless to say, it is also possible to add to be heterogeneously catalyzed the dehydrogenation of propane a mixture of water vapor and molecular hydrogen. The addition of molecular hydrogen to the heterogeneously catalyzed the dehydrogenation of propane reduces also the undesirable formation of allenes (PROPADIENE), propene and acetylene as by-products. Partial oxidation of such added hydrogen at the same time supplies the required heat of reaction.

Essential according to the invention is that as the reaction stage 1 can also be applied heterogeneously catalyzed partial dehydrogenation of propane, in which the type field, the Oia propane ranges from 20 to 30 mol.% (in terms of disposable passage of fresh propane through dehydration). Particularly beneficial for the method according to the invention as a reaction stage 1 heterogeneously catalyzed partial dehydrogenation of propane, in which the above conversion of propane ranges from 30 to 60 mol.%, preferably from 35 to 55 mol.% and particularly preferably from 35 to 45 mol.%. Other suitable interval conversion is 25, respectively, from 30 to 40 mol.%.

To implement the above conversion of propane beneficial if heterogeneously catalyzed dehydrogenation of propane is carried out at an operating pressure of 0.3 to 10 bar, respectively, up to 3 bar. Next favorably be heterogeneous catalytic dehydrogenation of propane to dilute with water vapor. The heat capacity of water allows thus, on the one hand, to balance the action of endothermy dehydrogenation, and, on the other hand, dilution steam reduces the partial pressure of the raw product and the reaction product, which positively affects the equilibrium of the dehydrogenation. Further, the use of water vapor beneficial, as already mentioned, for the life of noble metal containing catalysts, in particular in case of high conversion of propane to which you aspire. If you need another component may be added molecular hydrogen. The molar ratio of molecularbiology to propane in the initial reaction gas mixture 1 is usually ≤ 5. The molar ratio of water vapor to the propane in the original reaction gas mixture 1 is expedient way is ≥ 0.05 to 2, respectively, to 1.

Basically, the preferred small water vapor content in the original reaction gas mixture 1. During the conversion, in terms of fresh propane, in the range from 20 to 30 mol.% usually contained in recycled according to the invention, if necessary, the source of the reaction gas mixture 1 oxidative circulation gas, the amount of water vapor rather as supply water vapor heterogeneously catalyzed dehydrogenation. For higher, in terms of fresh propane, conversion of propane is usually, in addition, water vapor is added, in which we can speak, for example, about the pooled process is water.

In principle, acting as the reaction stage 1 heterogeneously catalyzed partial dehydrogenation can be carried out (as if) Grèsätzlich o adiabatically and endothermically. The source of the reaction gas mixture 1, as a rule, is first heated at a temperature from 500 to 700°C (respectively, from 550 to 650°C) (for example, direct burning of the surrounding wall). By adiabatic passage, at least one catalyst layer, the reaction gas mixture 1 is then cooled in the head of the dependence of conversion and dilution by approx. from 30°C to 200°C. the Presence of steam as a coolant preferably is manifested in adiabatic mode. Low temperature reactions allow longer service life applied catalyst layer. Higher temperatures lead to higher conversion.

From the point of view of technology use according to the invention it is expedient implementation of the heterogeneously catalyzed dehydrogenation of propane as a reactionary stage 1 shelf in the reactor.

It contains spatial consecutive more than one catalytic dehydrogenation catalyst layer. The number of catalyst layers may be from 1 to 20, an expedient manner from 2 to 8, but also from 3 to 6. With the increasing number of shelves achieved slightly increased conversion of propane. Catalyst layers are preferably radially or axially one behind the other. From the point of view of technology use reasonable manner in such shelf reactor catalyst layer is made as a fixed layer.

In the simplest case, the fixed catalyst layers in the reactor in the form of a shaft furnace is located axially or in the annular gaps centreceske inserted one into each of the cylindrical grate. However, it is also possible to position the ring C is the process in segments one above the other, and the gas after the radial passage in the segment to send to the next, lying above or below the segment.

Expediently, the reaction gas mixture 1 on its way from one catalyst layer to the next catalyst layer, for example, is subjected to intermediate heating shelf in the reactor by passing over heated by hot gases heat exchanger surfaces (e.g., ribs) or by passing through heated by hot gases of combustion pipe.

If shelving reactor is otherwise operated and o adiabatically, for the conversion, in terms of fresh propane, ≤ 30 mol.%, first of all, in the application described in the document DE-A 19937107 catalysts, especially in both examples the forms of execution, it is sufficient that the reaction gas mixture 1 is served in the dehydrogenation reactor preheated to a temperature of from 450 to 550°C and a shelf inside the reactor is kept in this temperature range. This means that the total dehydrogenation of propane should be carried out at such extremely low temperatures, which is a positive effect on the service life of fixed catalyst layers between two regenerations. For high conversion of propane reaction gas mixture 1 is expediently fed into the dehydrogenation reactor preheated to high temperatures (they can reach up to 700°C), and shelf inside of the reactor is derivada in this elevated temperature range.

Even more favorable to carry out the above-described intermediate heating by direct (autothermal mode). To do this, to the reaction gas mixture 1 is added or already before the passage of the first catalyst layer (then to the source of the reaction gas mixture 1 should podmahivat molecular hydrogen) and/or between subsequent catalyst layers in organic volume of molecular oxygen. So you can (usually catalyzed by the catalyst dehydrogenation) to provide a limited combustion contained in the reaction gas mixture 1, formed in the course of the heterogeneously catalyzed propane dehydrogenation and/or added to the reaction gas mixture of 1 molecular hydrogen (if necessary, accompanied by what is happening in a small volume of combustion of propane) (from the point of view of engineering applications, it is appropriate introduction to shelf the reactor catalyst layers, which are loaded with catalyst which is particularly specific (selective) catalyzes the combustion of hydrogen (as such catalysts are suitable, for example, described in documents US 4788371, US 4886928, US 5430209, US 5530171, US 5527979 and US 5563314 catalysts, such catalysts can be placed in alternating containing dehydrogenation catalyst layers in shelf reactor)). Released when e is om the heat of reaction allows autothermal way (total thermal effect is basically zero) almost isothermal mode of operation of the heterogeneously catalyzed partial dehydrogenation of propane. With increasing residence time of the reaction gas in the catalyst layer dehydrogenation of propane is possible with a decreasing or substantially constant temperature, which ensures a particularly long service life between two regeneration processes (in the boundary case to ensure avotermin can be burned also and only propane).

In General, according to the invention described above, the oxygen supply can be carried out in such a way that the oxygen content in the reaction gas mixture 1, in terms of the contained amount of molecular hydrogen, is from 0.5 to 50, respectively, to 30, preferably from 10 to 25 vol.%. As the source of oxygen thus suitable as a pure molecular oxygen or diluted with an inert gas, such as CO, CO2N2and/or noble gases oxygen, in particular air (not to mention circulating oxidative gas, preferably as a source of oxygen is air). Rezultiruja combustion gases, as a rule, are additionally razbavlau and contribute as a consequence, the heterogeneously catalyzed the dehydrogenation of propane. This really is especially formed within the combustion water vapor.

The isothermic parameter applicable to the method according to the invention are suitable the way as the reaction stage 1 heterogeneously catalyzed dehydrogenation of propane can be improved further by that shelf in the reactor in the spaces between the catalyst layers are placed favorably, however, does not necessarily evacuated the building (e.g., tubular). These contain built suitable solids or liquids that evaporate at temperatures above a certain or melt and consume the heat, and where the temperature is lowered again condense and release heat.

Needless to say, forming a reaction stage 1 heterogeneously catalyzed dehydrogenation of propane can be implemented as described in the document DE-A 10211275 (as "loopback option"), which forms an integral part of the present patent application.

This means that for the method according to the invention it is preferable if the reaction stage 1 can act heterogeneously catalyzed partial dehydrogenation of propane in the gas phase, in which

(B) to the dehydrogenation zone continuously fail containing subject to dehydrogenation of propane source of the reaction gas mixture 1,

C) the source of the reaction gas mixture 1 in the dehydrogenation zone is passed through at least one fixed catalyst layer, which are formed by catalytic dehydrogenation of molecular hydrogen and (partially) propylene,

D) before or after in the ode in the dehydrogenation zone to the starting reaction gas mixture 1 add at least one containing molecular oxygen gas,

E) molecular oxygen in the dehydrogenation zone in the reaction gas mixture 1 oxidizes contained in the reaction gas mixture of 1 molecular hydrogen partially in water vapor,

and

F) from the dehydrogenation zone select product gas which contains molecular hydrogen, water vapor, propylene and unreacted propane and which differs in that selected area dehydrogenation product gas is divided into two partial quantities of identical composition and one of both partial quantities as circulating gas dehydrogenation (preferably as a component of the original reaction gas mixture 1) recycle to the dehydrogenation zone as recommended in document WO 03/076370.

This oxidation of the circulating gas can be component of the source of the reaction gas mixture 1 and/or according to the document DE-A 102004032129 may be supplied to the reaction gas mixture 1 only after already partially occurred dehydrogenation.

If the oxidation of the circulating gas is a component of the original reaction gas mixture 1, it contains an expedient manner only derived from the oxidation of the circulating gas is molecular oxygen.

For the method according to the invention in the framework of the described loop dir is mA favorably, if the amount of circulating gas dehydrogenation, in terms of forming in the area of dehydrogenation product gas is from 30 to 70 vol.%, preferably from 40 to 60 vol.%, particularly preferably 50 vol.%.

Regarding the following according to the invention the reaction stages 2 and 3 of the original reaction gas mixture 1 contains in the case of, for example, a shelf in the reactor loop mode (shelf reactor with an internal circuit, then the dehydrogenation zone) in the steady state to be expedient:

15 to 25 vol.%propane
2 to 6 vol.%propylene
5 to 20 vol.%water vapor
2 to 10 vol.%molecular hydrogen
40 to 75 vol.%molecular nitrogen
>0 to 3%vol.molecular oxygen

Conversion of propane (in terms of single pass above the source of the reaction gas mixture 1 through operated in loop mode shelving reactor) and the ratio of the gas loop mode (the number is the amount of circulating gas dehydrogenation in terms of the total amount of product in the dehydrogenation zone) subject to the next according to the invention the two-stage heterogeneously catalyzed partial oxidation in the gas phase propylene selected from the advantage thus (for example, in a deck reactor with an internal circuit as the dehydrogenation zone)that formed in the dehydrogenation zone, the product gas contains unreacted propane and the desired propylene in a molar ratio of propene to propane and 0.25, respectively, 0.3 to 0.5 (if necessary, up to 0.66). When the ratio of gases in a looped mode of 0.5 corresponds to a conversion in a single pass of the source of the reaction gas 1 through the dehydrogenation zone contained propane from 15 to 25 mol.%.

Typical load catalyst layers dehydrogenation reaction gas mixture 1 is from 250 to 5000 h-1(at the highest load and up to 40,000 h-1), preferably 10000 to 25000 nl/l·h, particularly preferably 15000 to 20000 nl/l·h Corresponding load propane are typically from 50 to 1000 h-1(at the highest load up to 40,000 h-1), preferably from 2000 to 5000 nl/l·h, particularly preferably from 3000 to 4000 nl/l·h

Taken from the dehydrogenation zone (from the dehydrogenation reactor) as a source of propylene, the reaction stage 1) product gas dehydrogenation is in accordance with the selected for the heterogeneously catalyzed propane dehydrogenation conditions of the reaction at a pressure of from 0.3 to 10 bar, preference is sustained fashion from 1 to 3 bar, and is often a temperature of from 450 to 650°C., usually at temperatures ranging from 500 to 600°C. As a rule, it contains propane, propene, N2N2H2O, methane, ethane (the last two rezultirase due to thermal decomposition of small amounts of propane, ethylene, butene-1, other butenes, such as ISO-butene, other hydrocarbons, such as n-butane, ISO-butane, butadiene, etc., co and CO2and oxygenates, such as alcohols, aldehydes and carboxylic acids (usually with the number of carbon atoms ≤ 9). Further may contain a small amount originating from the oxidation of the circulating gas components.

While the documents EP-A 117146, DE-A 3313573 and US-A 3161670 recommend formed at oxidisation propane and/or dehydrogenation of propane gas as such to load the partial oxidation according to the invention, for the subsequent stage according to the invention the partial oxidation of propylene to acrylic acid preferably contains propylene product gas of the first stage reaction before applying it as a source for propene partial oxidation of propylene according to the invention to separate at least a partial quantity contained therein, other than propane and propylene components. It should comply with the requirements described in the document DE-A 10211275. This is the Department provides another opportunity for release other than propane and propylene side components with the method according to the invention.

According to the invention is separated, at least 50 vol.%, preferably, at least 75 vol.%, especially preferably at least 90 vol.% and even more preferably at least 95 vol.% contained in the product gas of the first stage reaction, other than propane and propylene components, before it is used for partial oxidation according to the invention. This is especially when the first stage of the reaction we are talking about a heterogeneously catalyzed partial dehydrogenation of propane.

Suitable for the needs of the method according to the invention is preferably cooled (preferably to a temperature of from 10 to 100, respectively, 70°C) product gas mixture of the dehydrogenation of propane and/or oxidisation, for example, at a pressure of from 0.1 to 50 bar, preferably from 5 to 15 bar and a temperature of, for example, from 0 to 100°C., preferably from 20 to 40°C, should be brought into contact with (preferably high-boiling organic solvent (preferably hydrophobic), which are absorbed propane and propylene (an expedient manner the preferred relative to other components of the product gas mixture of the dehydrogenation of propane and/or oxidisation) (for example, through a simple transmission). Subsequent desorption, rectification and/or strip what inhom via behaves inertly with respect to the partial oxidation according to the invention and/or required in this partial oxidation as reagent gas (e.g., air or another mixture of molecular oxygen and inert gas) can be obtained again propane and propylene in mixture in purified form, and this mixture applied for partial oxidation as a source of propylene (preferably proceed as described in comparative example 1 of document DE-A 102004032129). Containing, if necessary, molecular hydrogen othonoi gas such absorption can again be subjected to, for example, absorption with variable pressure and/or membrane separation (for example, according to DE-A 10235419) and then, if necessary, to apply the separated hydrogen.

However, the separation factor3-hydrocarbons/S4-hydrocarbons in the above method of separating relatively limited and often not sufficient to described in DE-A 10245585 needs. As an alternative the stage of separation of absorption, therefore, according to the invention often prefer rectification under pressure and absorption with variable pressure.

As the absorbent for the above absorption (absorption) of the Department suitable in principle all the absorbents, which are able to absorb propane (described below can separate propane and propylene from oxidative circulating gas and then as3-circulating gas to return to the first (and, in the case of the mu is a necessity, the next phase of the reaction). When the absorbent material, it is preferably an organic solvent, which preferably is hydrophobic and storable. Preferably, this solvent has a boiling point (at normal pressure of 1 ATM)at least 120°C, preferably at least 180°C., even more preferably from 200 to 350°C., in particular from 250 to 300°C., even more preferably from 260 to 290°C. Suitable way point flash point (at normal pressure of 1 bar) is more than 110°C. In General, as an absorbent suitable relatively non-polar organic solvents, such as aliphatic hydrocarbons, which preferably contain acting outside the polar group, but also aromatic hydrocarbons. In General, it is desirable, if the adsorbent has high a boiling point at simultaneously high solubility of propane and propylene. As the absorbent should for example be mentioned aliphatic hydrocarbons, such as C8-C20-alkanes or-alkenes, or aromatic hydrocarbons, such as middle oil fractions from paraffin distillation, or ethers with volume (steric complex) groups on the O-atom, or mixtures thereof, and to them may be added to a polar solvent, such as, for example, described the DE-A 4308087 1,2-dimethylphthalate. Further suitable esters of benzoic acid and talavou acid with unbranched, containing 1 to 8 atoms of carbon alkanols, such as a complex n-butyl ester of benzoic acid, methyl ester benzoic acid, complex ethyl ester of benzoic acid, dimethyl ether complex talavou acid diethyl ether complex talavou acid, and the so-called alonesee oils, such as diphenyl, simple diphenyl ether and mixtures of diphenyl and simple diphenyl ether or chlorinated and triarylamine, for example 4-methyl-4'-benzyl-difenilmetana and its isomers, 2-methyl-2'-benzyl-diphenyl-methane, 2-methyl-4'-benzylbiphenyl-methane and 4-methyl-2'-benzyl-difenilmetana and mixtures of such isomers. Suitable absorbent material is a solvent mixture of diphenyl and simple diphenyl ether, preferably in the azeotropic composition, in particular approx. 25 wt.% of diphenyl (biphenyl) and approx. 75 wt.% simple diphenyl ether, for example a commercially available Diphyl® (e.g., Bayer Aktiengesellschaft). Often this solvent mixture contains a solvent such as dimethylphthalate, in the amount of from 0.1 to 25 wt.%, in terms of the total solvent mixture. Particularly suitable absorbents are also octane, nonanes, decanes, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane and octade the Ana, especially suitable showed themselves tetradecane. Is favourable, if applicable absorbent, on the one hand, is above the boiling point, on the other hand, while not very high molecular weight. Preferably the molecular weight of the absorbent is ≤ 300 g/mol. Also suitable are described in the document DE-A 3313573 paraffin oil with 8 to 16 carbon atoms. Examples of these commercial products are supplied by the company Haltermann products, such as Halpasole i like Halpasol 250/340 i and Halpasol 250/275 i, as well as oils for printing inks called PKWF and Printosol. Preferred free from fragrances trade products, for example, type PKWFaf. If they contain small amounts of residual scents, it can be reduced before applying rectification and/or absorption and reduced to values below 1000 weight. million hours

Conducting absorption is not subject to any restrictions. Can be applied by any well-known specialist methods and conditions. Preferably the gas mixture at a pressure of from 1 to 50 bar, preferably from 2 to 20 bar, more preferably from 5 to 15 bar and the temperature from 0 to 100°C., in particular from 20 to 50, respectively, 40°C, can be brought into contact with the absorbent. The absorption can be carried out in columns, and extinguishing apparatus. You can wire the th reaction in the co-current or counter-current (preferred). Suitable absorption columns are, for example, column trays (with cap and/or sieve plates), columns with structured packings (for example, sheet packings with a specific surface of from 100 to 1000 or up to 750 m2/m3such as Mellapak® 250 Y) and Packed columns (for example, nozzles of the process). Can also be applied to cooling towers and spray towers, graphite block absorbers, surface absorbers such as thin - and thick-film absorbers, as well as the disc scrubber, mechanical spray scrubbers and rotary scrubbers. It can also be beneficial holding of absorption in a bubble column with rebuilding or without rebuilding.

The separation of propane and propylene from the absorber can be carried out by quenching, reducing evaporation (single instant evaporation and/or distillation.

The separation of propane and propylene from the absorber is preferably suppression and/or desorption. Desorption can be carried out in the usual way by changing the pressure and/or temperature, preferably at a pressure of from 0.1 to 10 bar, in particular from 1 to 5 bar, more preferably from 1 to 3 bar and at a temperature of from 0 to 200°C., in particular from 20 to 100°C., even more preferably from 30 to 70°C., particularly preferably from 30 to 50°C. Suitable for t is the solution gas is for example, hydrogen, a preferred mixture of oxygen, nitrogen, such as air. When using air, for example a mixture of oxygen and nitrogen, in which the oxygen content is more than 10 vol.%, it might make sense before and/or during the process of extinguishing add gas, which reduces the range of the explosion. Especially suitable for this are gases with specific heat capacity ≥ 29 j/mol·K at 20°C, as, for example, methane, ethane, propane (preferred; suitable fresh propane and/or C3-the circulation gas), propene, benzene, methanol, ethanol, and ammonia, carbon dioxide and water. With4-hydrocarbons according to the invention should be avoided as such additives. Especially suitable for extinguishing bubble columns with heads and without them.

The separation of propane and propylene from the absorber may be also carried out by distillation, respectively, by distillation, and can be applied well-known specialist columns with packings, gaskets or the relevant integrations. The preferred conditions for distillation, respectively, rectification are a pressure of from 0.01 to 5 bar, in particular from 0.1 to 4 bar, more preferably from 1 to 3 bar and the temperature in the lower portion of the column) from 50 to 300°C., in particular from 150 to 250°C.

Obtained by quenching from the absorber, suitable for subsequent stages of partial ocil is the source of propylene can before applying it to load partial oxidation to go to other stages of the method, so, for example, to reduce losses subject to extinguish the absorber (for example, the deposition of the shaped demisters and/or deep filters) and stage partial oxidation in a timely manner to protect from the absorber or to further improve the effect of separation between the C3-/C4-hydrocarbons. This separation of the absorber may be all well-known specialist stages of the method. One preferred within the framework of the method according to the invention form such separation is, for example, suppression of the original stream from the device evaporation of water. In this case, the adsorbent is washed from the loaded source of water flow, and the original thread at a time is loaded with water (small amounts are sposobstvuya on catalytic activity subsequent partial oxidation). This rinsing, respectively, the quenching may be carried out, for example, in the upper part of the desorption column through the absorbing liquid dish by countercurrent washing with water or in a private office.

To support the separating effect in space fighting can be placed to increase the surface of the extinguishing installation, well-known specialist in distillation, absorption and desorption.

Water is the preferred cleaning agent (detergent), because it usually does not interfere in the subsequent, IU the greater extent, one partial area. After the water washed the absorbent loaded from propane and propylene stream source, a mixture of water and absorber can be fed to a phase separation, and processed, poor volume source stream is fed directly to the partial oxidation according to the invention.

This preferred method according to the invention can be obtained when a mixture of propylene/propane from the absorbent pariveda with air, usually directly applied source of the reaction gas mixture 2. If the content of propane according to the invention is still not satisfactory, prior to their application for partial oxidation of the obtained propylene according to the invention it can even be added fresh propane. Through With3-the circulation gas (for example, oxidation of the circulating gas) he then returned to the reaction stage 1 (for example, in the heterogeneously catalyzed dehydrogenation (for example, as a component of the reaction gas source mix 1)). On the appropriate amount of propane, then, can be reduced fresh propane in the original reaction gas mixture 1 (in the General reaction stage 1). In the special case required for the reaction stage 1 (for example, the heterogeneously catalyzed propane dehydrogenation) fresh is Rapana can then completely fall away, if this fresh propane before conducting the partial oxidation of propylene according to the invention takes place entirely in the source of the reaction gas mixture 2 and/or 3, where it then as remaining component in the oxidation of circulating gas only after the passage of the partial oxidation according to the invention serves the source of the reaction gas mixture 1 (respectively, in the General reaction stage 1), for example, the heterogeneously catalyzed dehydrogenation of propane.

Part or full fresh propane can be done in the source of the reaction gas mixture 3 (however, the source of the reaction gas mixture 3 sometimes even then not explosive when this qualification is valid for the reaction of the source gas mixture 2). It is preferable, primarily because the unwanted side reaction of propane in Propionaldehyde and/or propionic acid, primarily emanates from the first reaction stage with its terms. Preferably also distribute fresh propane mostly evenly on the second and third reaction stage.

This supply of fresh propane in the source of the reaction gas mixture 2 and/or 3 can purposefully run the original composition of the reaction gas mixture 2 and 3 explosive. Decisive when answering questions is, whether the source of the reaction gas mixture 2, respectively, 3, hazardous or not, is distributes whether located under certain initial conditions (pressure, temperature) of the source of the reaction gas mixture 2, respectively, 3, caused by local ignition source (for example, incandescent platinum wire) combustion (ignition, explosion) or not (see standard DIN51649 and description in document WO 04/007405). If propagation occurs, the mixture in this description referred to as explosive. If no propagation occurs, the mixture in this description referred to as non-explosive. If the reaction of the source gas mixture 2, respectively, 3, non-explosive, it really is also formed during the partial oxidation of propylene according to the invention, the reaction gas mixture 2, respectively, 3 (cf. WO 04/007405).

Needless to say, required for the method according to the invention propane (fresh propane) can be brought fully to the starting reaction gas mixture 1. The present invention also relates to a preferred implementation of the method according to the invention, which is required for fashion propane (fresh propane) maximum part (for example, only 75%or only 50%or only 25%) is the source of the reaction gas mixture 1 and, at least partially (usually the residual amount, if necessary, the total number) is the source of the reaction gas mixture 2 (and/or source of the reaction gas mixture 3). However you can do, as described in document WO 01/96170, which forms an integral part of this application. Two-step partial oxidation of propylene according to the invention in the acrylic acid based on the fact that the heterogeneously catalyzed partial oxidation in the gas phase propylene to acrylic acid with molecular oxygen occurs in two following each other along the longitudinal coordinate of the stage, of which the first results acrolein and second leads from acrolein to acrylic acid.

The conduct of this interaction in two reaction stages allows the best fit for each of these two-stage oxidation catalyst fixed layer and, preferably, other reaction conditions, such as temperature of the fixed catalyst layer.

Suitable for each of these two reaction stages 2, 3 catalysts based on oxides of multimetallic known to the expert and described in the literature. For example, in document EP-A 253409 available on page 5 indication of the relevant U.S. patents.

Suitable catalysts for partial oxidation are described in the document is x DE-A 4431957, DE-A 102004025445 and DE-A 4431949. This is especially valid for the General formula I in both the above documents. Particularly preferred catalysts are described in DE-A 10325488, DE-A 10325487, DE-A 10353954, DE-A 10344149, DE-A 10351269, DE-A 10350812 and DE-A 10350822.

To the reaction stage 2 according to the invention, namely, the heterogeneously catalyzed partial oxidation in the gas phase propylene to acrolein, in principle, suitable all containing Mo, Bi and Fe mass on the oxide multimetallic as the active mass.

This is particularly active mass on the oxide multimetallic General formula I document DE-A 19955176, active mass on the oxide multimetallic General formula I document DE-A 19948523, active mass on the oxide multimetallic General formula I, II and III of the document DE-A 10101695, active mass on the oxide multimetallic General formula I, II and III of the document DE-A 19948248 and active mass on the oxide multimetallic General formula I, II and III of the document DE-A 19955168, as also described in EP-A 700714 active mass on the oxide multimetallic.

Next, to this reaction stage is suitable containing Mo, Bi and Fe catalysts based on oxides of multimetallic described in the documents DE-A 10046957, DE-A 10063162, DE-C 3338380, DE-A 19902562, EP-A 15565, DE-C 2380765, EP-A 807465, EP-A 279374, DE-A 3300044, EP-A 575897, US-A 4438217, DE-A 19855913, WO 98/24746, DE-A 19746210 (General formula II), JP-A 91/294239, EP-A 293224 and EP-A 700714. In particular, it really is, for example, for forms, issue the log, given in these documents, among which are described in the documents EP-A 15565, EP-A 575897, DE-A 19746210 and DE-A 19855913 especially preferred. especially it is necessary to emphasize in this connection, the catalyst according to example 1C from EP-A 15565, and obtained accordingly the catalyst, the active mass of which has the composition Mo12Ni6,5Zn2Fe2Bi1P0,0065K0,06Ox·10SiO2. Next, you should emphasize the example under number Nr. 3 from the document DE-A 19855913 (stoichiometry: Mo12Co4Fe3Bifor 0.6K0,08Si1,6Ox) as a catalyst for hollow cylinders with geometry 5 mm × 3 mm × 2 mm (external diameter × height × internal diameter)and a solid catalyst oxide multimetallic II according to example 1 of DE-A 19746210. Next, you should call the catalysts on oxide multimetallic from US-A 4438217. The latter in particular when these hollow cylinders with dimensions of 5.5 mm × 3 mm × 3.5 mm, or 5 mm × 2 mm × 2 mm, or 5 mm × 3 mm × 2 mm, or 6 mm × 3 mm × 3 mm, or 7 mm × 3 mm × 4 mm (external diameter × height × internal diameter). Other possible catalysts are the branches (for example, 7.7 mm in length and 7 mm in diameter; or 6.4 mm in length and 5.7 mm in diameter).

Many are suitable for the stage of conversion of propylene to acrolein active mass on the basis of oxides multimetallic may arise from the General Faure the uly IV:

,

in which the variables have the following meanings:

X1= Nickel and/or cobalt,

X2= thallium, an alkali metal and/or alkaline earth metal,

X3= zinc, phosphorus, arsenic, boron, antimony, tin, cerium, lead and/or tungsten,

X4= silicon, aluminum, titanium and/or zirconium,

a = from 0.5 to 5,

b = from 0.01 to 5, preferably from 2 to 4

C = from 0 to 10, preferably from 3 to 10,

d = from 0 to 2, preferably from 0.02 to 2,

e = from 0 to 8, preferably from 0 to 5,

f = from 0 to 10 and

n = the number determined by the valence and amount of non-oxygen elements in the IV.

They can be obtained in a known manner (see, for example, the document DE-A 4023239) and molded into balls, rings or cylinders and pre-molded in the form of a shell catalyst, i.e. covered with an active mass of preformed inert carrier. Needless to say, they can be used in powder form as catalysts.

In principle, active mass General formula IV are provided with an easy way of appropriate sources of their elemental constituents is prepared as possible well mixed, preferably finely dispersed dry mixture, the composition of which corresponds to its stoichiometry, and calicivirus at a temperature of from 350 to 650°C. the Calcification can be implemented the better in the atmosphere of inert gas, and under oxidizing conditions, for example in an atmosphere of air (mixture of inert gas and oxygen), and also in terms of recovery (for example, in an atmosphere of a mixture of inert gas, NH3, CO and/or H2). The duration of calcination can vary from several minutes to several hours and, as a rule, decreases with temperature. As the source of the elemental constituents of the active masses of polymetallic oxides IV use connections, which mean the oxides and/or compounds that, by heating, at least in the presence of oxygen, can be converted into oxides.

Along with oxides as starting compounds can be used, first of all, halides, nitrate, formate, oxalate, citrates, acetates, carbonates, complexes of amines, ammonium salts and/or hydroxides (compounds such as NH4OH, (NH4)2CO3, NH4NO3, NH4CHO2CH3COOH, NH4CH3CO2and/or ammonium oxalate, which at the latest when the late calcination can disintegrate and/or decompose to compounds that are completely evaporate into gaseous form and can be input in the composition of dense dry mix).

Thorough mixing of the starting compounds to obtain mass polymetallic is xadow IV can be performed in a dry or wet form. With stirring in a dry form of the original connection, it is expedient to use as fine powders and after mixing and possible concentration subjected to calcination. However, thorough mixing is preferably carried out in a wet form. While the parent compound is mixed, usually in the form of an aqueous solution and/or suspension. Especially thoroughly mixed dry mixture obtained when implementing the above method of mixing in that case originate from existing in the dissolved form sources of the elemental constituents. The solvent preferably use water. Then, the resulting water mass is dried, and the drying process is preferably carried out by spray drying the aqueous mixture at the exit temperature from 100 to 150°C.

Active mass polymetallic oxides of General formula IV can be molded to obtain a powder form or a specific geometry of the catalyst, and the molding can be performed before or after calcination. For example, a powder form of the active mass or its uncalcined and/or partially calcined initial mass by concentration and subsequent molding (for example, tableting, extrusion or extrusion) can be obtained catalyzatoroprovod form, moreover, if necessary, you can add auxiliary substances, such as graphite or stearic acid as lubricants and/or auxiliary agent for molding, as well as the active filler, such as microfibers of glass, asbestos, silicon carbide or potassium titanate. Suitable forms of the catalysts are, for example, filled or hollow cylinder outer diameter and the length of which ranges from 2 to 10 mm In the case of a hollow cylinder, the wall thickness should be from 1 to 3 mm. in Addition, the solid catalyst may be in the form of balls, and the diameter of the balls can vary from 2 to 10 mm

Particularly advantageous geometry of the hollow cylinder is 5 mm × 3 mm × 2 mm (external diameter × length × internal diameter), especially in the case of solid catalysts.

Needless to say, the molding powder of the active mass or powder uncalcined and/or partially calcinatory source mass can also be accomplished by applying preformed inert catalyst carriers. The coating on the carrier for receiving the shell catalysts, usually carried out in a suitable rotatable container, as described, for example, in DE-A 2909671, EP-A 293859 or EP-A 714700. Suitable for coating on the media powder mA is su moisturize and after the coating is then dried, for example, hot air. The thickness of the layer of powdered material is deposited on the carrier is usually from 10 to 1000 μm, preferably from 50 to 500 μm, particularly preferably from 150 to 250 microns.

As a material of the carrier can be used conventional porous or nonporous aluminum oxide, silicon dioxide, thorium dioxide, zirconium dioxide, silicon carbide or silicates such as magnesium silicate or aluminum silicate. They usually are inert in the implementation of the first stage target reaction method according to the invention. The media may not be correct or incorrect form, and preference is given to holders of regular shape with a pronounced surface roughness, for example balls or hollow cylinders. Suitable is the use of non-porous, rough, spherical media of steatite (for example, Steatite C220 CeramTec)whose diameter is from 1 to 8 mm, preferably from 4 to 5 mm also suitable as carriers is the use of cylinders whose length is from 2 to 10 mm (for example, 8 mm), and an external diameter of from 4 to 10 mm (for example, 6 mm). If used as carriers of the rings wall thickness typically is from 1 to 4 mm, are Preferred according to the invention the annular carriers have a length of from 2 to 6 m is, the external diameter of from 4 to 8 mm and a wall thickness of 1 to 2 mm According to the invention preference as carriers give first of all rings size 7 mm × 3 mm × 4 mm or 5 mm × 3 mm × 2 mm (external diameter × length × internal diameter). The dispersion applied to the surface of the carrier catalytically active oxide mass is chosen in accordance with the thickness of the bowl (see EP-A 714700).

Suitable active masses polymetallic oxides for the second reaction stage are then mass General formula V:

,

in which the variables have the following meanings:

Y1means only bismuth or bismuth and at least one of the elements tellurium, antimony, tin and copper,

Y2means molybdenum or molybdenum and tungsten,

Y3means of alkali metal, thallium and/or samarium,

Y4mean alkaline earth metal, Nickel, cobalt, copper, manganese, zinc, tin, cadmium and/or mercury,

Y5means iron or iron and at least one of the elements chromium and cerium,

Y6mean phosphorus, arsenic, boron and/or antimony,

Y7means rare earth metal, titanium, zirconium, niobium, tantalum, rhenium, ruthenium, rhodium, silver, gold, aluminum, gallium, indium, silicon, germanium, lead, thorium and/or uranium,

and' means from 0.01 to 8

b' means from 0.1 to 30,

s means from 0 to 4,

d' is from 0 to 20,

e' > from 0 to 20,

f is from 0 to 6,

g' is from 0 to 15,

h' means from 8 to 16,

x', y' denote the number of which is determined by the valence and amount of non-oxygen elements in the formula II, and

p,q means the number, the ratio p/q is from 0.1 to 10,

which contain three-dimensional remote from each other, limited to your local environment on the basis of their non-local environment, structure chemical composition of the Y1a'Y2b'Ox'the largest diameter (the longest passing through the center of gravity of the area of the connecting segment two located on the surface (boundary surface) of the region of points) is from 1 nm to 100 μm, frequently from 10 nm to 500 nm or from 1 μm to 50 or 25 μm.

Especially preferred mass polymetallic oxides II are those in which Y1means bismuth.

Among them, preference is given to those that are characterized by the General formula VI:

in which the variables have the following meanings:

Z2means molybdenum or molybdenum and tungsten,

Z3mean Nickel and/or cobalt,

Z4means thallium, an alkali metal and/or alkaline earth metal,

Z5mean phosphorus, arsenic, boron, antimony, tin, cerium and/or light of the EC,

Z6means silicon, aluminum, titanium and/or zirconium,

Z7means copper, silver and/or gold,

and means from 0.1 to 1,

b” means from 0.2 to 2,

with means ranging from 3 to 10,

d” means from 0.02 to 2,

E. means from 0.01 to 5, preferably from 0.1 to 3,

f” means from 0 to 5,

g” means from 0 to 10,

h” means from 0 to 1,

x”, y” means the number determined by the valence and amount of non-oxygen elements in the formula III, and

p”, q” means the number, the ratio p/q” which is from 0.1 to 5, preferably from 0.5 to 2,

with the greatest preference is given to the masses VI, in which Z2bmeans (tungsten) b” and Z212means (molybdenum)12.

In addition, preferred are those of mass, in which at least 25 mol. % (preferably at least 50 mol. % and especially preferably at least 100 mol. %) total content [Y1a'Y2b'Ox']p([BiaZ2bOx”]p) suitable according to the invention masses polymetallic oxides V (mass polymetallic oxides VI) used according to the invention the mass polymetallic oxides V (masses polymetallic oxides VI) represent a three-dimensional remote from each other, Lok limited to your the school environment on the basis of their non-local environment, structure chemical composition of the Y 1a'Y2b'Ox'[BiaZ2bAboutx”), the largest diameter of which is from 1 nm to 100 μm.

The molded mass polymetallic oxides of V has a power all of the above in the case of catalysts based on mass polymetallic oxides IV.

Getting active mass polymetallic oxides of V are described, for example, in EP-A 575897, as well as in DE-A 19855913.

Misericordiae inert carrier suitable as inert materials for dilution and/or restrictions of the respective fixed catalyst layers, respectively, as their protective and/or heating the gas mixture prior to backfilling.

For the third reaction stage heterogeneously catalyzed oxidation partial oxidation in the gas phase of acrolein to acrylic acid, in principle, suitable all containing Mo and V the mass of the oxides multimetallic as active mass required for catalysts, for example, described in document DE-A 10046928.

A large number of these masses polymetallic oxides, for example, described in document DE-A 19815281, characterized by the General formula VII:

,

in which the variables have the following meanings:

X1means W, Nb, TA, Cr and/or CE,

X2mean Cu, Ni, Co, Fe, Mn and/or Zn,

X3means Sb or Bi,

X4means one or more alkali metals,

X5means one or more alkaline earth metals

X6means Si, Al, Ti and/or Zr,

and means from 1 to 6,

b means from 0.2 to 4,

with means of 0.5 to 18,

d is from 0 to 40,

E. means from 0 to 2,

f is from 0 to 4,

g means from 0 to 40 and

n means the number that is determined by the valence and amount of non-oxygen elements in the formula VII.

The preferred forms of implementation of the active masses of the polymetallic oxides VII according to the invention are those in which the variables of the General formula VII have the following meaning:

X1means W, Nb and/or Cr,

X2mean Cu, Ni, Co and/or Fe,

X3means Sb,

X4means Na and/or K,

X5means of CA, Sr and/or BA,

X6means Si, Al and/or Ti,

and means from 1.5 to 5,

b means from 0.5 to 2,

with means of 0.5 to 3,

d is from 0 to 2,

E. means from 0 to 0.2,

f denotes from 0 to 1, and

n means the number that is determined by the valence and amount of non-oxygen elements in the formula VII.

The most preferred polymetallic oxides VII according to the invention are the oxides of the General formula VIII:

in which:

Y1means W and/or Nb,

Y2mean Cu or Ni,

Y5mean CA and/or Sr,

Y6means Si and/or Al,

and' means from 2 to 4

b' means from 1 to 1.5,

with' means 1 to 3,

f' denotes from 0 to 0.5,

g' is from 0 to 8 and

n' means the number that is determined by the valence and amount of non-oxygen elements in the formula VIII.

Suitable according to the invention the active mass polymetallic oxides (VII) can be obtained, for example, described in DE-A 4335973 or EP-A 714700 ways.

In principle suitable for the stage "acrolein - acrylic acid (the third reaction stage) active mass polymetallic oxides, especially those that are characterized by the General formula VII can be obtained in a simple way: from the respective sources of their elemental constituents is prepared as tight, preferably finely dispersed dry mixture, the composition of which corresponds to its stoichiometry, and calicivirus at a temperature of from 350 to 650°C. the Calcification can be in the atmosphere of inert gas and oxidizing conditions, for example in an atmosphere of air (mixture of inert gas and oxygen), and recovery (for example, in an atmosphere of a mixture of inert gas and reducing gases such as H2, NH3, CO, methane and/or acrolein or themselves in the atmosphere of reducing gases). The duration for which licencie can vary from several minutes to several hours and, as a rule, decreases with temperature. As the source of the elemental constituents of the active masses of polymetallic oxides VII use connections, which mean the oxides and/or compounds that, by heating, at least in the presence of oxygen, can be converted into oxides.

Thorough mixing of the starting compounds to obtain mass polymetallic oxides VII can be carried out in dry or wet form. With stirring in a dry form of the original connection, it is expedient to use as fine powders and after mixing and possible concentration subjected to calcination. However, thorough mixing is preferably carried out in a wet form.

Typically, the parent compound is mixed in the form of an aqueous solution and/or suspension. Especially thoroughly mixed dry mixture obtained when implementing the above method of mixing in that case originate from existing in the dissolved form sources of the elemental constituents. The solvent preferably use water. Then, the resulting water mass is dried, and the drying process is preferably carried out by spray drying the aqueous mixture at the exit temperature from 100 to 150°C.

Active mass polimet lychesky oxides, especially those that are characterized by the General formula VII, in the process of partial oxidation of acrolein to acrylic acid according to the invention can be used both in powder form and in the appropriate form of the catalyst, and the molding can be performed before or after calcination. For example, a powder form of the active mass or not calcined initial mass by concentration and subsequent molding (for example, tableting, extrusion or extrusion), it is possible to obtain the catalyst of the necessary forms, and, if necessary, you can add auxiliary substances, such as graphite or stearic acid as lubricants and/or auxiliary agent for molding, as well as the active filler, such as microfibers of glass, asbestos, silicon carbide or potassium titanate. Suitable forms of the catalysts are, for example, filled or hollow cylinder outer diameter and the length of which ranges from 2 to 10 mm In the case of a hollow cylinder, the wall thickness should be from 1 to 3 mm. in Addition, the catalyst may be in the form of a ball, the diameter can be from 2 to 10 mm (e.g., 8.2 m or 5.1 mm).

Of course, the molding powder of the active mass or not calcined powder of the original mass mo is but also to make by drawing on pre-formed inert catalyst carriers. The coating on the carrier for receiving the shell catalysts, as a rule, is carried out in a suitable rotating vessel, as described, for example, in DE-A 2909671, EP-A 293859 or EP-A 714700.

Suitable for coating on the media powder mass moisturize and after the coating is then dried, for example, hot air. The thickness of the layer of powdered material is deposited on the carrier is usually from 10 to 1000 μm, preferably from 50 to 500 μm, particularly preferably from 150 to 250 microns.

As a material of the carrier can be used conventional porous or nonporous aluminum oxide, silicon dioxide, thorium dioxide, zirconium dioxide, silicon carbide or silicates such as magnesium silicate or aluminum silicate. The media may not be correct or incorrect form, and preference is given to holders of regular shape with a pronounced surface roughness, for example balls or hollow cylinders. Suitable is the use of non-porous, rough, spherical media of steatite, the diameter of which ranges from 1 to 10 mm, preferably, for example, 8 mm, preferably from 4 to 5 mm also suitable as carriers is the use of cylinders whose length is from 2 to 10 mm and an external diameter of from 4 to 10 mm In the case of the use which has been created as carriers of the rings wall thickness, as a rule, is from 1 to 4 mm, are Preferred according to the invention the annular carriers have a length of from 3 to 6 mm, an external diameter of from 4 to 8 mm and a wall thickness of 1 to 2 mm According to the invention preference as carriers give first of all rings size 7 mm × 3 mm × 4 mm (external diameter × length × internal diameter). The dispersion applied to the surface of the carrier catalytically active oxide mass is chosen according to the thickness of the shell (see EP-A 714700).

Suitable active masses polymetallic oxides used for the partial oxidation of acrolein to acrylic acid according to the invention are also mass General formula IX:

,

in which the variables have the following meanings:

D means Mo12VaZ1bZ2c”Z3dZ4eZ5fZ6gOx”,

E. means Z712CuhHi”Oy,

Z1means W, Nb, TA, Cr and/or CE,

Z2mean Cu, Ni, Co, Fe, Mn and/or Zn,

Z3means Sb and/or Bi,

Z4means of Li, Na, L, Rb, Cs and/or N,

Z5means Mg, CA, Sr and/or BA,

Z6means Si, Al, Ti and/or Zr,

Z7means Mo, W, V, Nb and/or TA, preferably Mo and/or W,

and” means from 1 to 8

b” means the t 0.2 to 5,

with means from 0 to 23

d” denotes from 0 to 50,

e” denotes from 0 to 2,

f” means from 0 to 5,

g” means from 0 to 50,

h” means from 4 to 30,

i mean from 0 to 20 and

x”, y” means the number determined by the valence and amount of non-oxygen elements in the formula IX, and

p, q mean number other than zero, the ratio p/q which is from 160:1 to 1:1,

and that get therefore: mass polymetallic oxide E:

,

translated in finely dispersed form (initial weight of 1) and then pre-cooked solid active mass 1 is introduced into an aqueous solution, aqueous suspension or fine dry mixture of sources of the elements Mo, V, Z1, Z2, Z3, Z4, Z5, Z6that contain the above elements in the stoichiometric ratio D:

(initial mass 2), in the desired quantitative ratio p:q, thus obtained aqueous mixture is dried, and the resulting dry mass before or after its drying calicivirus at a temperature of from 250 to 600°C to obtain the desired shape of the catalyst.

Preference is given to the masses polymetallic oxides IX, in which the introduction of pre-prepared solid initial mixture of 1 in water source mass 2 is carried out at t is mperature < 70°C. Obtaining catalysts containing mass polymetallic oxides VI, described in detail, for example, in EP-A 668104, DE-A 19736105, DE-A 10046928, DE-A 19740493 and DE-A 19528646.

All of the above in relation to the active masses of the polymetallic oxides catalysts IX also applies to the formation of the active masses of polymetallic oxides catalysts VII.

For the stage "acrolein - acrylic acid" is a nice way suitable catalysts for the masses oxide multimetallic described in DE-A 19815281, in particular, with the active mass on the oxide multimetallic General formula I of this document.

It is preferable for the stage propylene to acrolein used hollow catalyst rings, and for the stage of acrolein to acrylic acid are used shell catalyst rings.

The implementation of the second reaction stage partial oxidation of propylene to acrolein, can be carried out with the described catalysts, for example (in shell-and-tube reactors; from the point of view of engineering applications located in the shell-and-tube capacity, the number of contact tubes is at least 5000, preferably at least 10000, often from 15,000 to 30,000; the number above 40000 forms most likely to be an exception within the capacity of the contact tube in the normal case of homogeneous distributed, and the distribution expediently selected so about what atom, that the distance of the Central internal axes to lying closer to each other the contact tubes (the so-called distribution of the contact tubes) is from 35 to 45 mm (see, for example, the document EP-A 468290); as heat exchangers are suitable in particular thermostatic liquid environment; it can be a molten salt, such as potassium nitrate, potassium nitrite, sodium nitrite and/or sodium nitrate, or viscoplastic metals such as sodium, mercury and alloys of different metals), single zone stationary reactor with a lot of contact tubes, as described, for example, in the document DE-A 4431957. While the reaction gas mixture 2 and the coolant (heat exchange medium) can be sent through the reactor in the direct current or counter-current.

The reaction pressure is usually from 1 to 3 bar and the total volumetric load of the fixed catalyst reaction layer (source) gas mixture 2 is preferably from 1500 to 4000, respectively, 6000 nl/l·h or more. Load propylene (load propylene fixed catalyst layer) is usually 90 to 200 nl/l·h, or up to 300 nl/l·h or more, load propylene above 135 nl/l·h, respectively, ≥ 140 nl/l·h, or ≥ 150 nl/l·h, or ≥ 160 nl/l·h according to the invention is preferred as the source of the reaction gas mixture 2 according to the invention and the method according to the obreteniyu determine favorable hot spot (all of the above truly independent from a special selection fixed catalyst).

Preferably single zone Novotrubny reactor with a fixed catalyst flown load gas mixture on top. As the heat exchange means is expediently salt solution, preferably consisting of 60 wt.% potassium nitrate (KNO3) and 40 wt.% sodium nitrite (NaNO2or out of 53 wt.% potassium nitrate (KNO3), 40 wt.% sodium nitrite (NaNO2) and 7 wt.% sodium nitrate (NaNO3).

Looking along the reactor, as already mentioned, the salt melt and reaction gas mixture 2 serves as a forward flow and backflow. Himself molten salt preferably sent around the contact tube in the form of a meander.

If the contact tubes are washed reaction mixture from the top down, it is advisable to load the contact tube catalyst from the top down as follows (with the flow of the reaction mixture from the bottom up download has a reverse order):

- first in length from 40 to 80, respectively, to 60% of the length of the contact tube or only the catalyst or the mixture of catalyst and inert material, the latter, in terms of the mixture, has weights up to 20 wt.% (segment);

- then in length from 20 to 50, respectively, up to 40% of the total length of the contact tube or only the catalyst or the mixture of catalyst and inert material, the latter, calculated on the mixture, it is no weights up to 40 wt.% (cut In);

in conclusion, in length from 10 to 20% of the total length of pipe the filling of inert material (segment a), which is preferably chosen so that it makes possible a low pressure loss.

Preferably cut With no problem.

The above download option especially suitable when used as a catalyst the catalysts according to example 1 of the document DE-A 10046957 or according to example 3 of document DE-A 10046957 and as inert material rings made of steatite with dimensions of 7 mm × 7 mm × 4 mm (external diameter × height × internal diameter). Regarding temperature salt baths really contained in document DE-A 4431957.

The implementation of the second reaction stage partial oxidation of propylene to acrolein (and, if necessary, acrylic acid), can be carried out with the described catalysts or, for example, in a two-zone novotrubnom the reactor with a porous layer, as described in DE-A 19910506. According to the invention the partial oxidation of propene to acrolein is carried out as described in EP-A 1159244, and especially preferably, as described in WO 04/085363 and WO 04/085362, however, under the conditions according to the invention for UP.

The documents EP-A 1159244, WO 04/085363 and WO 04/085362 considered as an integral part of the present description.

This means that the second re is kionna stage, partial oxidation of propylene to acrolein, particularly preferably carried out in a fixed catalyst layer with a high load of propylene, which has at least two temperature zones.

This means that the preferred form of the method according to the invention is that the reaction gas source mix 2 send through (over the catalyst fixed bed) fixed catalyst layer 2, the active mass of which is a containing at least the elements Mo, Fe and Bi oxide multimetallic, with the condition that the conversion of propylene in a single pass does not exceed a predetermined according to the invention is UP(the selectivity of the formation of acrolein and formation of by-product acrylic acid is evenly ≥ 90 mol.%) and characterized in that:

B) loading the catalyst fixed layer 2 contained in the reaction gas source of a mixture of 2-propene is ≥ 140, respectively, ≥ 160 nl of propene/l of fixed catalyst layer 2·h,

C) fixed catalyst layer 2 is located in two spatially successive reaction zones A*,* fixed catalyst layer 2, and the temperature of the reaction zone a* ranges from 300 to 390°C and the temperature, R is the promotional zone* ranges from 305 to 420°C and simultaneously lies, at least 5°C above the temperature of the reaction zone a*,

D) the reaction gas source mix 2 flows through the reaction zone And*,* in the time sequence "first A*","*",

E) the reaction zone a* extends up to a conversion of propene from 40 to 80% values UPseek to the second reaction stage according to the invention.

In other respects, reference is made to the document EP-A 1159244.

It also means that the special form of the second stage according to the invention lies in the way in which the reaction gas source mix 2 is passed through a fixed catalyst layer 2, the active mass of which represents at least one containing the elements Mo, Fe and Bi oxide multimetall, provided that:

- fixed catalyst layer 2 is placed in two spatially successive temperature zones a, b,

as the temperature of temperature zone a and the temperature of temperature zone lies in the range from 290 to 380°C,

- fixed catalyst layer 2 consists of at least two spatially successive zones of the fixed catalyst layer, and the specific volume of activity within a zone fixed catalyst layer mainly constant and abrupt increases in the direction of flow of the reaction gas mixture 2 in the transition from one zone fixed catalyst layer to another area of the fixed catalyst layer,

- reaction zone a* extends up to a conversion of propene from 40 to 80% values UPseek to the second reaction stage according to the invention,

- in a single pass of the reaction gas source mix 2 through the entire fixed catalyst layer conversion of propene has the value UPand selectivity of the formation of acrolein, calculated on converted propene is 90 mol.%,

- the sequence in time in which the reaction gas mixture 2 passes temperature zones a, b, corresponds to uzbekovoy sequence temperature zones

- load fixed catalyst layer 2 contained in the reaction gas source mix 2 propylene 90 nl propene / l of fixed catalyst layer 2·h,

- the difference between the TmaxA-TmaxBformed the highest temperature TmaxAthat is, the reaction gas mixture 2 within the temperature zone a, and the highest temperature TmaxBthat is, the reaction gas mixture 2 within the temperature zone is 0°C,

and additionally differs in that the transition temperature zones And in the temperature zone In the catalyst in a fixed bed 2 does not coincide with the transition from one zone of the fixed catalyst layer to another area of the fixed catalyst layer.

More precisely the s data on this method can be found in document WO 04/085362, which is an integral part of the present description and in the following text with the description of a particularly preferred form of the second and third reaction stage of the method according to the invention. The third reaction stage, namely the partial oxidation of acrolein to acrylic acid may be carried out with the above-described catalysts (in shell-and-tube reactors; according to the technique of applying a number of contact tubes, placed in a shell-and-tube reactor is at least 5000, preferably at least 10000, often 15000 to 30000; number of above 40,000 constitutes the exception rather inside the tank in the normal case the contact of the pipe evenly distributed, and the distribution expediently selected in such a way that the distance of the Central internal axes from each other next to each other contact tubes (so called the distribution of the contact tubes) is from 35 to 45 mm (cf, for example, the document EP-A 468290); as the heat exchange medium is suitable in particular thermostatic liquid environment; they can be melts of salts such as potassium nitrate, potassium nitrite, sodium nitrite and/or sodium nitrate, or melting at a low temperature metals such as sodium, mercury and alloys of various metals; an expedient manner as the other is, and the third reaction stage is carried out in such shell-and-tube reactors), for example, in single zone novotrubnom the reactor with a porous layer, as described in document DE-A 4431949. While the reaction gas mixture 3 and the coolant is directed, when viewed along the reactor, a direct current. According to the invention the product gas mixture 2 previous partial oxidation of propylene to acrolein basically goes as such (if necessary after made its intermediate cooling (it may occur directly or indirectly through the additive secondary air)), i.e. without separation of the side components, the third reaction stage, i.e. partial oxidation of acrolein.

Required for the third stage, for partial oxidation of acrolein, molecular oxygen can (in this case) is already contained in the reaction gas source mixture 2 for the reaction stage 2 according to the invention (partial oxidation of propylene to acrolein) (it is preferable according to the invention). However, it may partially or completely be submitted directly to the product gas mixture 2 of the first reaction stage is preferably as (secondary) air, but may also be in the form of pure oxygen or mixtures of inert gas or sour what kind).

As for the second reaction stage, and the third reaction stage, the reaction pressure is in the range from 1 to 3 bar and the total load of the fixed catalyst layer 3, the reaction gas (the source) mixture 3 is preferably about 1500 to 4000, respectively, 6000 nl/l·h or more. Load acrolein (load acrolein fixed catalyst layer 3) is usually from 90 to 190 nl/l·h or up to 290 nl/l·h or more, the load acrolein above 135 nl/l·h, respectively ≥ 140 nl/l·h, or ≥ 150 nl/l·h, or ≥ 160 nl/l·h are particularly preferred because the presence of propane in the reaction gas original mix 3 also leads to favorable hot spot.

Preferably single zone Novotrubny reactor with a fixed catalyst layer is loaded gas mixture 3 from above. As the heat exchange medium and the second reaction stage is used expediently salt melt, preferably consisting of 60 wt.% potassium nitrate (KHO3) and 40 wt.% sodium nitrite (NaNO2or out of 53 wt.% potassium nitrate (KHO3), 40 wt.% sodium nitrite (NaNO2) and 7 wt.% sodium nitrate (NaNO3). Looking along the reactor, salt melt and reaction gas mixture 3 serves as the co-current and counter-current. Himself molten salt preferably served around ontactnig pipes in the form of a meander.

If the stream is served at the contact tube top down, it is advisable to download the contact tube from top to bottom as follows:

- first in length from 50 to 80, respectively, up to 70% of the length of the contact tube or only a catalyst or mixture of catalyst and inert material, the latter, in terms of the mixture, has weights up to 20 wt.% (segment);

after this length from 20 to 40% of the total length of the pipes or just the catalyst or the mixture of catalyst and inert material, the latter, in terms of the mixture, has weights up to 50, respectively, to 40 wt.% (cut In);

in conclusion, in length from 5 to 20% of the total length of pipe the filling of inert material (segment a), which is selected preferably in such a way that it makes possible a low pressure loss.

Preferably cut With no problem. In General occurs when heterogeneously catalyzed partial oxidation in the gas phase of acrolein to acrylic acid (especially at high loads acrolein fixed catalyst layer 3 and the high content of water vapor boot gas mixture 3), a line segment may consist of two successive catalyst dilutions (to reduce the temperature of the hot spot and the sensitivity to temperature of the hot spot). From the bottom up with the achala up to 20 wt.% inert material and then > 20 wt.% up to 50, respectively, to 40 wt.% inert material. A line is then preferably diluted.

For flow in the contact tube from the bottom up loading contact tubes is carried out expediently in reverse order.

The above download option preferably suitable when used as catalysts, the catalysts according to exemplary embodiment 5 of the document DE-A 10046928 or according to the document DE-A 19815281 and as inert material - rings made of steatite with dimensions of 7 mm × 7 mm × 4 mm or 7 mm × 7 mm × 3 mm (each external diameter × height × internal diameter). Regarding temperature salt baths really contained in document DE-A 4431949. It is chosen, as a rule, in such a way that the conversion of acrolein, striving according to the invention, UAis achieved in a single pass.

Partial oxidation of acrolein to acrylic acid can be carried out with the described catalysts, for example, in a two-zone novotrubnom reactor with a fixed catalyst layer described in the document DE-19910508. For the conversion of acrolein really above. Also in this case, to obtain the boot of the gas mixture (the reaction gas original mix 3) is applied directly to the product gas mixture 2 (in case the e necessary after carried out directly or indirectly (for example through secondary air) intermediate cooling) (as already described above). Required for partial oxidation of acrolein oxygen is supplied preferably in air quality (if necessary, also as a pure molecular oxygen or a mixture of molecular oxygen and inert gas) and, for example, is added directly to the product gas mixture 2 of the first stage of two-stage partial oxidation (propylene to acrolein). However, it may already be contained in the reaction gas source mixture 2 for the second reaction stage according to the invention is preferred.

When the described two-stage partial oxidation of propylene to acrylic acid with immediate further use of the product gas mixture of the first stage partial oxidation, as a rule, connect in series two single zone Novotrubny reactor with a fixed catalyst layer (at higher load fixed catalyst layer, in General, indeed, the preferred flow regime between the reaction gas and salt bath (coolant)or two dual-zone Novotrubny reactor with a fixed catalyst layer. Mixed serial connection (odnokanal the nogo/two-zone or Vice versa) is also possible. "Single zone" at the stage of propene to acrolein and "two-zone" at the stage of acrolein to acrylic acid is favorable.

Between the reactors may be an intermediate cooler, which, if necessary, may contain a filling of inert material that can perform the filter function. The temperature of the salt bath novotrubnogo reactor for the first stage of two-stage partial oxidation of propylene to acrylic acid generally ranges from 300 to 400°C. the temperature of the salt bath novotrubnogo reactor for the second stage partial oxidation of acrolein to acrylic acid is in most cases from 200 to 350°C. furthermore, the heat exchange means (preferably molten salt) is passed through Novotrubny the reactor with a fixed catalyst layer in such quantities that the difference between their input and their output temperature is typically ≤ 5°C.

It should be mentioned that part of the reaction gas source mixture 2 for the first stage ("propylene to acrolein") may be coming from the partial oxidation of oxidation of the circulating gas (residual gas).

It is, as already mentioned, about containing molecular oxygen gas which remains after the separation of the target product (Department of acrolein and/or acrylic KIS is the notes) from the product gas mixture of the partial oxidation and partly can be recycled as inert gas diluent to load for the first and/or, if necessary, the second stage partial oxidation of propylene to acrolein and/or acrylic acid.

Preferably according to this invention containing propane, molecular oxygen and unreacted propylene oxidation of the circulating gas is recycled exclusively on the first, which serves as a source of propylene, the reaction stage (for example, the heterogeneously catalyzed dehydrogenation of propane).

In General one shell-and-tube reactor, inside which changes the loading of the catalyst along the individual contact tubes at the left end of the reaction stage (similar to the two-stage partial oxidation of propylene in the so-called "Single-reactor are described, for example, in documents EP-A 911313, EP-A 979813, EP-A 990636 and DE-A 2830765), constitutes the simplest form of implementation of both oxidation stages for both stages of the partial oxidation of propylene to acrylic acid. If necessary, download the contact tubes catalyst is interrupted while an inert filling.

Preferably both oxidation steps are implemented in the form of two connected in series shell and tube systems. These systems can be in the same reactor, and the transition from one tube bundle to another bundle of tubes is formed outside the contact tube (suitable way having the ability is of bhoga) filling of inert material. While the contact tube, as a rule, washed with brine, he reaches placed as described above, the filling of inert material. With the advantage of both beam contact of the tube is placed in a spatially separated from each other reactors. As a rule, between the two shell-and-tube reactors is an intermediate cooler to decrease occurring in case you need additional burning acrolein in the product gas mixture 2, which leaves the second reaction stage.

The reaction temperature in the second reaction stage (propylene to acrolein) is generally from 300 to 450°C., preferably from 320 to 390°C. the reaction Temperature of the third reaction stage (acrolein to acrylic acid) is generally from 200 to 370°C., often from 220 to 330°C. the Pressure of the reaction of both stages of oxidation ranges from 0.5 to 5, preferably from 1 to 3 bar. Load (nl/l·h) oxidation catalysts, the reaction gas is at both stages from 1500 to 2500 nl/l·h, respectively, up to 4000 nl/l·h Load propylene could be on the reactivity of stage 2 from 100 to 200 or 300 nl/l·h

In principle, both the reactionary stage of oxidation in the method according to the invention can be prepared in such a manner as described, for example, in documents DE-A 19837517, DE-A 19910506, DE-A 19910508, and so is e DE-A 19837519. In both reaction stages when this excess of molecular oxygen relative to the required stoichiometry of the reaction number has a positive effect on the kinetics of the corresponding partial oxidation in the gas phase.

Naturally when the form of the two-stage partial oxidation according to the invention of propylene to acrylic acid is made as two connected in series stages of oxidation, leaving the first stage oxidation product gas mixture may be partially or completely separated therein, formed in the first stage of oxidation as a by-product carbon dioxide and water vapor when needs before further submission to the second stage of oxidation. Preferably choose this method according to the invention, this separation does not.

As a source for held between the two stages of oxidation intermediate oxygen supply is suitable, as already mentioned, along with air (preferably) as a pure molecular oxygen or diluted with an inert gas, such as CO2, CO, noble gases, N2and/or saturated hydrocarbons with molecular oxygen. Also oxides can be added as sources of oxygen.

By means of additives, for example, cold air is to hot product gas mixture 2 may, within the scope of the method according to the invention be achieved by direct cooling of the mixture, before it is used as an integral part of the reaction gas original mix 3.

Preferably according to the invention the partial oxidation of acrolein to acrylic acid is carried out as described in document EP-A 1159246 and especially preferably as described in WO 04/085365, as well as in WO 04/085370. While it is preferable according to the invention as containing acrolein reaction gas original mix 3 applies the product gas mixture of the partial oxidation according to the invention of propylene to acrolein, which, if necessary, complemented by such an amount of secondary air that the ratio of molecular oxygen to acrolein in rezultirase reaction gas original mix 3 in any case is from 0.5 to 1.5. The documents EP-A 1159246, WO 04/08536 and WO 04/085370 considered as an integral part of the present description.

This means that partial oxidation according to the invention of acrolein to acrylic acid is preferably carried out on fixed catalyst layer 3 with high load acrolein, which contains at least two temperature zones.

This means that the predominant form of the partial oxidation according to the invention of acrolein to acrylic acid (reaction stage 3) represents the way in to the torus of the reaction gas original mix 3 skip over (through) catalyst(th) stationary(St) layer (layer) 3, the active mass of which is a containing at least one of the elements Mo and V oxide multimetallic, with the condition that the conversion acrolein in a single passage reaches the target value UA(the associated selectivity of the formation of acrylic acid is regularly ≥ 90 mol.%), which differs in that:

B) loading the catalyst fixed layer 3 is contained in the reaction gas original mix 3 acrolein is 130, respectively, ≥ 150 nl acrolein/l of fixed catalyst layer 3·h,

C) fixed catalyst layer 3 is located in the following two in space one after the other reaction zones C*, D* fixed catalyst layer 3, and the temperature of the reaction zone With a* ranges from 230 to 270°C. and the temperature of the reaction zone D* is from 250 to 300°C and simultaneously lies, at least 5°C above the temperature of the reaction zone With*,

D) the reaction gas original mix 3 flows through the reaction zone With a*, D* in sequence by time: "first*", "D*",

E) the reaction zone With* extends up to a conversion of arolina from 55 to 85 mol.% persecuted in the third reaction stage according to the invention the values of UA.

It also means that a special form of execution according to the invention concludes the I in the way, in which the reaction gas source mixture 3 is passed through a fixed catalyst layer 3, the active mass of which represents at least one containing the elements Mo, V oxide multimetall, provided that:

- fixed catalyst layer 3 is placed in the following two in space one after the other temperature zones C, D,

as the temperature of temperature zone, and the temperature of temperature zone D lies in the range from 230 to 320°C,

- fixed catalyst layer 3 consists of at least two spatially successive zones of the fixed catalyst layer, and the specific volume of activity within a zone fixed catalyst layer mainly constant and abrupt increases in flow direction of reaction gas mixture 3 in the transition from one zone fixed catalyst layer to another area of the fixed catalyst layer,

- the reaction zone extends up to a conversion of acrolein from 45 to 85% of the value UAseek in the third reaction stage according to the invention,

- in a single pass of the reaction gas original mix 3 through the entire fixed catalyst layer conversion of propene has the value UAand selectivity of the formation of acrylic acid, in terms of TA is built acrolein, 90 mol.%,

- the sequence in time in which the reaction gas mixture 3 passes temperature zones C, D, corresponds to uzbekovoy sequence temperature zones

- load fixed catalyst layer 3 is contained in the reaction gas original mix 3 acrolein 90 nl acrolein /l of fixed catalyst layer 2·h, and

- the difference between the TmaxC-TmaxDformed the highest temperature TmaxCthat is, the reaction gas mixture 3 within the temperature zone C and the highest temperature TmaxDthat is, the reaction gas mixture 3 within the temperature zone D is 0°C,

and additionally differs in that the transition temperature zone in the temperature zone D in the fixed catalyst layer 3 does not coincide with the transition from one zone of the fixed catalyst layer to another area of the fixed catalyst layer.

More accurate data concerning this method can be found in document WO 04/085362, which is an integral part of the present description and in the following text with the description of a particularly preferred form of a two-stage partial oxidation of propylene to acrylic acid.

Such particularly preferred two-stage partial oxidation of propylene is and to acrylic acid can be carried out, as described in the document EP-A 1159248 and WO 04/085367. Both documents form an integral part of the present description.

This means that the reaction gas source mix 2 in the second reaction stage 2 first pass over (through) catalyst(th) stationary(St) layer (layer 2, the active mass of which represents at least one containing the elements Mo, Fe and Bi oxide multimetallic, with the condition that the conversion of propylene in a single passage reaches the value UPseek according to the invention, and the associated selectivity of the formation of acrolein and formation of by-product acrylic acid is ≥ 90 mol.%, the temperature leaving the second reaction stage product gas mixture 2 direct and/or indirect cooling, if necessary, reduce to a product gas mixture 2 add, if necessary, molecular oxygen and/or inert gas, then as containing acrolein, molecular oxygen and at least one inert gas, the reaction gas source mixture 3, which contains the molecular oxygen and the acrolein in a molar ratio of About2:C3H4O≤0.5, and the third reaction stage is directed over (through) catalyst(th) stationary(St) layer (layer 3, the active mass of catalogoplantillas an at least one containing molybdenum and vanadium oxide multimetallic with the condition that the conversion acrolein in a single passage reaches the value UAseek according to the invention, and the selectivity of the formation of acrylic acid in both reaction stages, in terms of converted propylene, is 80 mol.%, while doing so, that:

B) loading the catalyst fixed layer 2 contained in the reaction gas source mix 2 propylene is ≥ 140, respectively, ≥ 160 nl propene/l of fixed catalyst layer 2·h,

C) fixed catalyst layer 2 is located in the following two in space one after the other reaction zones And*,* fixed catalyst layer 2, and the temperature of the reaction zone a* ranges from 300 to 390°C and the temperature of the reaction zone In* ranges from 305 to 420°C and simultaneously lies, at least 5°C above the temperature of the reaction zone a*,

D) the reaction gas source mix 2 flows through the reaction zone And*,* in sequence by time-first And*","*",

E) the reaction zone a* extends up to a conversion of propene from 40 to 80% values UPseek to the first reaction stage according to the invention,

F) loading the catalyst fixed layer 3 is contained in the reaction is ionic gas original mix 3 acrolein 120, accordingly, 140 nl arolina/l of fixed catalyst layer 3·h,

G) fixed catalyst layer 3 is located in the following two in space one after the other reaction zones C*, D* fixed catalyst layer 3, and the temperature of the reaction zone With a* ranges from 230 to 270°C. and the temperature of the reaction zone D* is from 250 to 300°C and at the same time lies at least 10°C. above the reaction zone With*,

N) reaction gas original mix 3 passes through the reaction zone With a*, D* in sequence by time "first*", "D*",

I) the reaction zone With* extends up to a conversion of acrolein from 55 to 85% of the value UAseek to the first reaction stage according to the invention.

In other respects, reference is made to the document EP-A 1159248.

Especially preferably the oxidation is carried out, as described in document WO 04/085369, which is an integral part of the present description.

This means that the first reaction gas source mix 2 in the second reaction stage are sent over the fixed catalyst layer 2, the active mass of which represents at least one containing the elements Mo, Fe and Bi oxide multimetallic, provided that:

- fixed catalyst layer 2 is located in the following two each for the other is in space temperature zones A, In,

as the temperature of temperature zone a and the temperature of temperature zone b is a temperature in the range from 290 to 380°C,

- fixed catalyst layer 2 consists of the two following each other in space zones fixed catalyst layer, and the specific volume of selectivity within a zone fixed catalyst layer in the core is constant and in the direction of flow of the reaction gas mixture 2 in the transition from one zone fixed catalyst layer to another area of the fixed catalyst layer is abruptly increased,

- temperature zone And extends to the conversion of propene from 40 to 80 mol.% values UPseek according to the invention in a second reaction stage,

- in a single pass of the reaction gas source mix 2 through a common catalyst fixed bed conversion of propene is the value of UPseek according to the invention, and the selectivity of the formation of acrolein and formation of by-product acrylic acid in General is based on converted propene, ≥ 90 mol.%,

sequence in time, according to which the reaction gas mixture 2 passes through temperature zones a, b, corresponds to the alphabetic sequence of temperature zones a, b

- load fixed catalyst layer 2 contained in the reaction gas source of a mixture of 2-propen 90 nl of propene/l of fixed catalyst layer 2·h, and

- the difference between the TmaxA-TmaxBformed from the highest temperature TmaxAthat is, the reaction gas mixture 2 within the temperature zone a, and the highest temperature TmaxBthat is, the reaction gas mixture 2 within the temperature zone is ≥ 0°C,

after that, the temperature leaving the second reaction stage product gas mixture 2 reduce, if necessary, cooled and the product gas mixture 2, if necessary, add molecular oxygen and/or inert gas, preferably, if necessary, the air, in conclusion, as containing acrolein, molecular oxygen and at least one inert gas, the reaction gas source mixture 3, which contains the molecular oxygen and the acrolein in a molar ratio of About2:C3H4O≥0.5, and the third reaction stage is directed through the fixed catalyst layer 3, the active mass of which represents at least one containing the elements Mo and V oxide multimetallic, provided that:

- fixed catalyst layer 3 is located in the following two in the space of each on the natives temperature zones, D

as the temperature of temperature zone, and the temperature of temperature zone D is a temperature in the range from 230 to 320°C,

- fixed catalyst layer 3 consists of at least two of the following in the space of successive zones of the fixed catalyst layer, and the specific volume of activity within a zone fixed catalyst layer mainly constant and in the direction of flow of the reaction gas mixture 3 in the transition from one zone fixed catalyst layer to another area of the fixed catalyst layer is abruptly increased,

- temperature zone extends up to a conversion of acrolein from 45 to 85% of the value UAseek in the third reaction stage,

- in a single pass of the reaction gas original mix 3 through a common fixed catalyst layer 3 conversion acrolein is the value of UAseek according to the invention, and the selectivity of the formation of acrolein, in terms of transformed both reaction stages propene is ≥ 80 mol.%,

sequence in time, according to which the reaction gas mixture 2 passes through the temperature zones C, D, corresponds to the alphabetic sequence of temperature zones C, D,

- load fixed catalyst layer 3 with urashima in the reaction gas source of a mixture of 3-propene is 70 nl acrolein/l of fixed catalyst layer 3·h, and

- the difference between the TmaxC-TmaxDformed from the highest temperature TmaxCthat is, the reaction gas mixture 3 within the temperature zone C and the highest temperature TmaxDthat is, the reaction gas mixture 3 within the temperature zone D is ≥ 0°C,

with the proviso that the method further distinguished by the fact that neither the transition from temperature zone a to temperature zone In the catalyst in a fixed bed 2 or the transition from temperature zone in the temperature zone D in the fixed catalyst layer 3 does not coincide with the transition from one zone of the fixed catalyst layer to another area of the fixed catalyst layer.

Under the temperature of one temperature zone at the same time refers to the temperature in the temperature range part of the fixed catalyst layer in the process, however, in the absence of chemical reactions. If this temperature is within the temperature zone is not constant, then the concept of temperature is the same temperature zones implies srednekamennogo temperature value fixed catalyst layer along the reaction zone. Significant is the fact that the tempering separate temperature zones occur independently of each other.

Due to the fact that as a heterogeneously catalyzed partial oxidation in the gas phase is of Rapana to acrolein, and heterogeneously catalyzed partial oxidation in the gas phase of acrolein to acrylic acid is a distinct exothermic reaction, as the temperature of the reaction gas mixture 2 and the temperature of the reaction gas mixture 3 when the reaction passes through the fixed catalyst layer 2, respectively, fixed catalyst layer 3, as a rule, different from the temperature of one temperature zone. Usually it lies above the temperature of temperature zone and is held within the temperature zone, as a rule, the maximum value (the maximum hot spot) or falls on the basis of the maximum value.

Generally, the method according to the invention the difference between the TmaxA-TmaxBis not more than 80°C. According to the invention is preferably the difference between the TmaxA-TmaxBis ≥ 3°C and ≤ 70°C. Particularly preferably, the difference TmaxA-TmaxBwith the method according to the invention is ≥ 20°C and ≤ 60°C.

Required according to the invention the difference of the TmaxA-TmaxBset during execution of the method according to the invention rather low values (≥ 90 nl/l·h and ≤ 160 nl/l·h) load propene catalyst fixed layer usually when one side as the temperature of the reaction zone a and the temperature of the reaction zone lies In the range from 290 to 380°C and on the other hand the difference between the temperature of the reaction zone (T Band the temperature of the reaction zone And (TA), i.e., TB-TAis ≤ 0°C and ≥ 20°C or ≥ 10°C, respectively, ≤ 0°C and ≥ 5°C or often ≤ 0°C and ≥ 3°C.

When performing the method according to the invention at higher (according to the invention preferred) load propene (≥ 160 nl/l·h and ≤ 300 nl/l·h or ≤ 600 nl/l·h) required according to the invention the difference of the TmaxA-TmaxBusually installed when with one hand as the temperature of the reaction zone a and the temperature of the reaction zone is in the range from 290 to 380°C and TB-TAis ≥ 0°C and ≤ 50°C or ≥ 5°C and ≤ 45°C or ≥ 10°C and ≤ 40°C or ≥ 15°C and ≤ 30°C ≤ 35°C (e.g., 20°C or 25°C).

Above regarding the difference of temperatures TB-TAvalid when the temperature of the reaction zone And lies within the preferred range from 305 to 365°C, respectively, in a particularly preferred interval from 310 to 340°C.

Load propene fixed catalyst layer can be described in the way of ≥ 90 nl/l·h and ≤ 300 nl/l·h, or ≥ 110 nl/l·h and ≤ 280 nl/l·h or ≥ 130 nl/l·h and ≤ 260 nl/l·h, or ≥ 150 nl/l·h and ≤ 240 nl/l·h, or ≥ 170 nl/l·h and ≤ 220 nl/l·h, or ≥ 190 nl/l·h and ≤ 200 nl/l·h

According to the invention preferably the temperature zone And extends to the conversion of propene from 50 to 70%, respectively, of which 60 to 70% of the value U Pseek according to the invention in the second reaction stage.

Generally, the method according to the invention the difference between the TmaxC-TmaxDis not more than 75°C., Preferably according to the invention the difference between the TmaxC-TmaxDis 3°C and 60°C., Especially preferably in the method according to the invention the difference between the TmaxC-TmaxDis ≥ 5° C or ≥ 40°C.

Required according to the invention the difference of the TmaxC-TmaxDset during execution of the method according to the invention in the case of rather low (components ≥ 70 nl/l·h and ≤ 150 nl/l·h) loads acrolein fixed catalyst layer 3 is usually when one side as the temperature of the reaction zone and the temperature of the reaction zone D is in the range from 230 to 320°C and on the other hand the difference between the temperature of the reaction zone D (TDand the temperature of the reaction zone (TC), i.e., TD-TCis ≥ 0°C and ≥ 20°C or ≥ 10°C, respectively ≤ 0°C and ≥ 5°C or often is ≤ 0°C and ≥ 3°C.

In the process according to the invention at elevated pressures by propene and that at higher loads acrolein (150 nl/l·h and 300 nl/l·h, respectively 600 nl/l·h) required according to the invention the difference of the TmaxC-TmaxDare usually when on the one hand to the to the temperature of the reaction zone, and the temperature of the reaction zone D is in the range from 230 to 320°C and TD-TCis ≥ 0°C and ≤ 40°C or ≥ 5°C and ≤ 35°C 30°C or ≥ 10°C and ≤ 25°C, respectively, ≤ 20°C or ≤ 15°C.

The above relative difference of temperatures TD-TCvalid when the temperature of the reaction zone lies within the preferred range from 250 to 300°C, respectively, in a particularly preferred range of from 260 to 280°C.

Load acrolein fixed catalyst layer 3 may, when the method according to the invention can be, for example, ≥ 70 nl/l·h, respectively, ≥ 90 nl/l·h and ≤ 300 nl/l·h, or ≥ 110 nl/l·h and ≤ 280 nl/l·h, or ≥ 130 nl/l·h and ≤ 260 nl/l·h, or ≥ 150 nl/l·h and ≤ 240 nl/l·h, or ≥ 170 nl/l·h and ≤ 220 nl/l·h, or ≥ 190 nl/l·h and ≤ 200 nl/l·h

Preferably according to the invention the temperature zone extends up to a conversion of acrolein from 50 to 85%, respectively, 60 to 85% of the value UAseek in the third reaction stage.

Working pressure can both reaction stages to lie as below normal pressure (for example up to 0.5 bar)or above normal pressure. Typical operating pressure for both reaction zones lies at values of from 1 to 5 bar, frequently from 1 to 3 bar.

Typically, the pressure response to both reaction zones do not exceed the t 100 bar. The selectivity of the formation of the product prescribed in the second reaction stage (the amount of education acrolein and formation of by-product acrylic acid) is in this case known per se suitable choice (see recommended at this stage catalyst) catalyst fixed layer 2 according to the invention ≥ 92 mol.%, or ≥ 94 mol.%, often ≥ 95 mol.%, or ≥ 96 mol.%, accordingly, ≥ 97 mol.%.

Generally, when the above-described method, the load acrolein fixed catalyst layer 3 is at least 10 nl/l·h, frequently, at least 20, respectively, 25, or at least 30, 40, or at least 50 nl/l·h lower load propene catalyst fixed layer 2. This is due primarily to the fact that in the second reaction stage, the conversion of propene is limited according to the invention.

When known in itself, a suitable choice of the fixed catalyst layers 2 and 3 (see recommendations on the catalysts in the present description) when carrying out the above method according to the invention balanced on both reaction stages selectivity of the formation of acrylic acid, calculated on converted propene, is according to the invention regularly ≥ 83 mol.%, often ≥ 85 mol.%, or ≥ 88 mol.%, often ≥ 90 mol.%, or ≥ 93 m the l%.

Essential to this process is that the catalyst fixed bed 2 consists of at least two of the following in the space of successive zones of the fixed catalyst layer, and the specific volume of activity within a zone fixed catalyst layer mainly constant and in the direction of flow of the reaction gas mixture 2 in the transition from one zone fixed catalyst layer to another area of the fixed catalyst layer increases abruptly. Specific volume (i.e. normalized to the unit of the corresponding volume of backfill) activity one zone fixed catalyst layer may be installed on district fixed catalyst layer mainly constant way due to the fact that originate from the primary quantity produced in a uniform way catalyst molded product (filling corresponds to the maximum attainable specific volume activity) and their homogeneous diluted in the appropriate area of the fixed catalyst layer behaving largely inert with respect to the heterogeneously catalyzed partial oxidation in the gas phase molded products (molded products-thinners). The higher the share of molded-thinners, the less are contained in a certain volume sasip and active mass, accordingly, the catalyst activity. As materials for such inert shaped products diluents suitable in principle all those which are also suitable as carriers for shell catalysts according to the invention.

As such materials are suitable, for example, porous or nonporous aluminum oxide, silicon dioxide, thorium dioxide, zirconium dioxide, silicon carbide, silicates such as magnesium silicate or aluminum or the already mentioned steatite (for example, Steatit C-220 CeramTec).

Geometric shape such inert molded-thinners may be in principle any. This means that there may be balls, polygons, solid cylinders or rings. According to the invention preferably in an inert molded-thinners choose such a geometric shape corresponding to a geometric form, subject to dilution of their catalyst molded products.

According to the invention is favorable, if the chemical composition of the applied active mass around the fixed catalyst layer 2 is not changed. This means that is used to separate the catalyst molded active mass may however be a mixture of different, containing the elements Mo, Fe and Bi oxides multimetallic, for all katalysator the x molded catalyst fixed layer 2 should then apply the same mixture.

Increasing in flow direction of reaction gas mixture 2 along the fixed catalyst layer 2 zones specific volume activity can be configured in a simple manner to the described method, for example, due to the fact that filling in the first zone catalyst fixed layer start with a high proportion of inert molded-thinners, in terms of sort of the catalyst molded product, and then this portion of the molded part is thinner in the direction of flow in zones lower.

Rising on areas specific volume activity are also possible due to the fact that at the unchanged geometry and type of active mass moulded products shell of the catalyst increases by zone thickness supported on a carrier layer of active mass or in a mixture of shell catalysts with the same geometry, but with different weight fractions of active mass increase in the zones share a catalyst molded products with high share of active mass. Alternatively, you can dilute the very active mass due to the fact that when getting active mass, for example, be calcining the dry mixture of the source compounds produce an inert, current razbavlau materials such as vysokokvalicifirovannye silicon dioxide. Various additional number is as applicable razbavlau material lead automatically to different activities. The more you add the current razbavlau material, the less rezultirase activity. A similar effect can be achieved, for example, due to the fact that when mixtures of solid catalysts and of the shell catalysts (with identical active mass) appropriately changing the mixing ratio. Further can be obtained by a variant-specific volume activity through the use of geometry catalyst with different bulk density (for example, when solid catalysts with identical composition of the active masses of different geometries). Needless to say, the described options may be combined.

Naturally for a fixed catalyst layer 2 can also be used a mixture of catalysts with chemically different compounds active compounds and, as a consequence, different composition, different activity. These mixtures can vary according to the zones in their composition and/or can be diluted with various amounts of inert molded-thinners.

Before and/or at the end of the fixed catalyst layer 2 may be composed exclusively of inert material (for example, only moulded products-thinners) backfill (in the present description terminology they are not classified as fixed catalyst layer, t the to as they do not contain molded products, who have active weight based on the oxides multimetallic). When this is applied to inert backfill moulded products-thinners may have the same geometric shape as used in the fixed catalyst layer 2 catalyst molded product. The geometric shape used for inert backfill molded-thinners may also differ from the geometric shaped catalyst molded product (for example, in the form of beads instead of rings).

Applied for such inert fillings moulded products often have an annular shape with geometry 7 mm × 7 mm × 4 mm (external diameter × length × internal diameter) or shape of balls with diameter d=4-5 mm Temperature zones a and b may extend in the method according to the invention also inert backfill. Preferably according to the invention as temperature zone a and the temperature zone In each including not more than three zones fixed catalyst layer (force according to the invention, at least one zone of the fixed catalyst layer is enclosed on both temperature zones).

Especially preferred according to the invention the overall fixed catalyst layer 2 includes no more than five, an expedient manner not more than four, respectively, three zones catalyst not dignaga layer.

The transition from one zone of the fixed catalyst layer to another (in the direction of flow of the reaction gas mixture 2) fixed catalyst layer 2 (with a single active mass around the fixed catalyst layer 2) specific volume weight (i.e. the weight contained in the uniform charging amount of active mass on the oxide multimetallic) according to the invention should be increased by at least 5 wt.%, preferably, at least 10 wt.% (this is true in particular when a single catalyst molded products across the fixed catalyst layer 2). Typically, this increase with the method according to the invention is not more than 50 wt.%, in most cases, not more than 40 wt.%. Further, when a single active mass around the fixed catalyst layer, the difference in specific volume of the active mass 2 area fixed catalyst layer with the lowest specific volume activity and area fixed catalyst layer with the highest specific volume activity shall be not more than 50 wt.%, preferably not more than 40 wt.% and, as a rule, not more than 30 wt.%.

Often, when the method according to the invention fixed catalyst layer 2 consists of only two zones fixed catalyst layer.

According to the invention, prepact the tion of the latter in the direction of flow of the reaction gas mixture 2 area fixed catalyst layer nerozbalena. This means that it is preferably entirely of catalyst molding. If necessary it can also consist of a single filling of the catalyst molded products, specific volume activity of which is reduced, for example by dilution with an inert material, for example, by 10%.

If fixed catalyst layer 2 consists of only two zones fixed catalyst layer according to the invention, preferably, as a rule (as in common with the method according to the invention), if the area of the fixed catalyst layer with the higher specific volume of activity is not included in the temperature zone (in particular if in temperature zone a and the temperature range In the tempering is carried out using a fluid coolant, which flows in countercurrent to the reaction gas mixture). This means that favorable area fixed catalyst layer with the lowest specific volume of activity is in the temperature zone In and zone fixed catalyst layer with high specific volume activity begin and end in the temperature zone C. This means that they start behind the transition from temperature zone a to temperature zone B.

If fixed catalyst layer 2 consists of only the three zones of the fixed catalyst layer, according to the invention, preferably, if the area of the fixed catalyst layer with the higher specific volume of activity is not included in temperature zone a, And starts and ends in temperature zone B, i.e. has its origin behind the transition from temperature zone a to temperature zone (in particular if in temperature zone a and the temperature range In the tempering is carried out using a fluid coolant, which flows in countercurrent to the reaction gas mixture). This usually means that in this case the zone of the fixed catalyst layer with the second largest highest specific volume activity includes both in temperature zone a and the temperature zone C.

If fixed catalyst layer 2 consists of four zones of the fixed catalyst layer, as a rule, according to the invention, preferably, if the area of the fixed catalyst layer with the third highest specific volume of activity is in the temperature zone a and the temperature zone (in particular if in temperature zone a and the temperature range In the tempering fluid is a coolant, which flows in countercurrent to the reaction gas mixture 2).

In the case of the reaction gas mixture 2 in parallel with the coolant temperatury zones a and b may have the advantage, if the method according to the invention within the fixed catalyst layer 2 stationary catalyst layer with the highest specific volume of activity is in the temperature zone A.

Basically, the specific volume of activity between the two zones fixed catalyst layer 2 can be determined experimentally in a simple way so that when identical framework conditions (preferably the conditions of the present method) at fixed catalyst layers of the same length, but each time in accordance with the composition of the catalyst zone fixed layer, guide containing the same propene reaction gas mixture. Most transformed number of propene shows the highest specific volume activity.

If the total length of the fixed catalyst layer 2 is equal to L1according to the invention, preferably, if the rangeaccordingly, in the rangeaccordingly, in the rangeis not the transition from one zone fixed catalyst layer to another zone, and X means the place (position) within the fixed catalyst layer 2, in which the transition from temperature zone a to temperature zone C.

It is preferable for the above pic is BA catalyst fixed bed in flow direction of reaction gas mixture 2 is structured as follows.

First, in length from 10 to 60%, preferably from 10 to 50%, particularly preferably from 20 to 40% and even more preferably from 25 to 35% (i.e., for example, the length of from 0.70 to 1.50 m, preferably from 0.90 to 1.20 m) total length of the fixed catalyst layer 2 a homogeneous mixture of the catalyst molded and molded-thinners (both have basically the same geometric shape, and weight fraction of molded-thinners (mass density catalyst molded product and the molded products of different diluents, generally, only minimal) is usually from 5 to 40 wt.%, or from 10 to 40 wt.%, or from 20 to 40 wt.%, or from 25 to 35 wt.%. In conclusion, this first zone catalyst fixed layer are then preferably before the end of the length of the fixed catalyst layer (i.e. the length of from 2.00 to 3.00 m, preferably from 2.50 to 3.00 m), or diluted only in a small volume (the first area) backfilling catalyst molded product, or, particularly preferably, only (undiluted) filling those catalyst molded product, which was used in the first zone. The above really especially when the catalyst in a fixed bed as a catalyst molded apply ring solid catalyst or oliza shell of the catalyst (especially those which in the present description are referred to as preferred). With the advantage within the above structure as a catalyst molded product and the molded product is thinner in the method according to the invention are mainly the geometry of the rings 5 mm × 3 mm × 2 mm (external diameter × length × internal diameter).

The above is also valid when instead of molded-thinners applied molded products shell catalyst, the proportion of active mass which is from 2 to 15 wt.% lower than the proportion of active mass is applied, if necessary, at the end of the fixed catalyst layer 2 molded shell catalyst.

Pure inert filling, the length of which, in terms of the length of the fixed catalyst layer 2, an expedient manner is from 5 to 20%, starting in the direction of flow of the reaction gas mixture 2, as a rule, fixed catalyst layer 2. It is generally used as the heating zone of the reaction gas mixture 2. Instead of filling with an inert material as a heating zone can also be used diluted with an inert material catalyst filling.

According to the invention is preferably in the above fixed catalyst layers area fixed catalyst layer is less specific volume activity extends another 5 to 20%, often 5 to 15% of its length in the temperature zone of the Century

An expedient manner the temperature zone And extends also applied in case of need for fixed catalyst layer 2 pre-filling of inert material.

Essential to the advantages of the described method according to the invention is further that the fixed catalyst layer 3 consists of at least two spatially successive zones of the fixed catalyst layer, and the specific volume of activity within a zone fixed catalyst layer in the core is constant and in the direction of flow of the reaction gas sweep 3 when moving from one zone fixed catalyst layer to another increases abruptly. Specific volume (i.e. normalized to the unit of the corresponding volume of backfill) activity zone fixed catalyst layer can be installed basically a constant image area of the fixed catalyst layer in such a way that emanate from the core of the quantity produced in a uniform way catalyst molded product (filling corresponds to the maximum received specific volume activity) and their homogeneous dilute in each zone of the fixed catalyst layer behaving mostly inert from siteline heterogeneously catalyzed partial oxidation in the gas phase molded products (molded products-thinners). The higher the selected portion of the molded part is thinner, the lower is contained in a certain volume of backfill active mass, respectively, the activity of the catalyst. As materials for such inert shaped products diluents suitable in principle all those which are also suitable as carrier materials for the shell catalyst according to the invention.

As such materials are suitable, for example, porous or nonporous aluminum oxide, silicon dioxide, thorium dioxide, zirconium dioxide, silicon carbide, silicates such as magnesium silicate or aluminum or the already mentioned steatite (for example, steatite C-220 CeramTec).

Geometric shape such molded products-thinners may in principle be any. This means that can be used bulbs, polygons, solid cylinders or rings. According to the invention preferably in an inert molded choose such a geometric shape corresponding to a catalyst molded product.

According to the invention is favorable this embodiment, in which the chemical composition of the applied active mass does not change around the fixed catalyst layer 3. This means that applied to separate the molded catalyst products active mass can b the th mixture of different, containing the elements Mo and V oxides multimetallic, for all catalyst molded catalyst fixed layer 3 should apply the same mixture.

Growing zones in the flow direction of the reaction gas mixture 3 is fixed catalyst layer 3 specific volume activity can be installed in a simple way, for example, due to the fact that filling in the first zone catalyst fixed layer starting with a high proportion of inert molded-thinners in terms of sort of the catalyst molded and then this portion of the molded part is thinner in the direction of flow in zones lower.

Improving on areas specific volume activity is also possible due to the fact that at the unchanged shape and form of the active mass moulded products shell of the catalyst increases by zone thickness supported on a carrier layer of active mass or in a mixture of shell catalyst with the same geometry, but with different weight fractions of active mass increase in the zones share a catalyst molded product with a higher weight fractions of the active mass. Alternative you can also active mass to dilute so that upon receipt of the active mass, for example, is subject to calcination su is th the mass of the parent compounds produce inert existing razbavlau materials, such as visocosity silicon dioxide. Various formulations of the current razbavlau material lead automatically to a different activity. The more you add razbavlau active material, the lower will be the resulting activity. A similar effect can be obtained, for example, due to the fact that when mixtures of solid catalysts and of the shell catalysts (with identical active mass) accordingly changes the mixture ratio. Then one option is specific to the volume of activity can be obtained by applying the geometrical shape of the catalyst with different bulk density (for example, when solid catalysts with identical composition of the active masses of different geometric shapes). Needless to say, the described options can also be combined.

Naturally for a fixed catalyst layer 3 can also be used a mixture of catalysts with chemically different composition of active mass and, as a consequence, different composition with different activity. These compounds can areas vary in their composition and/or can be diluted with various amounts of inert molded-thinners.

Before and/or at the end of the fixed catalyst layer 3 may be composed exclusively of inert material the material (for example, only moulded products-thinners) backfill (they are not considered in the present description to a fixed catalyst layer 3, because they do not contain molded products that have active mass on the oxide multimetallic). When used for inert backfill moulded products-thinners may have the same geometric shape as the filling fixed catalyst layer. The geometric shape used for inert backfill molded-thinners may also differ from the above geometric shaped catalyst molded product (for example, saricoban instead of a circle).

Often used for such fillings molded products have the ring geometric shape of 7 mm × 7 mm × 4 mm (external diameter × length × internal diameter) or a spherical shape with a diameter d=4-5 mm Temperature zones C and D can with the method according to the invention extend to an inert filling. Preferably according to the invention as temperature zone, and the temperature zone D includes no more than three zones fixed catalyst layer according to the invention by force, at least one zone of the fixed catalyst layer captured both temperature zones.).

According to the invention particularly preferably, if the total rolled is mash the fixed layer 3 includes no more than five, an expedient manner not more than four, respectively, of the three zones of the fixed catalyst layer.

The transition from one zone of the fixed catalyst layer to another area of the fixed catalyst layer (in the direction of flow of the reaction gas mixture 3) the specific volume of the active mass (with a single active mass around the fixed catalyst layer 3) (i.e. the weight contained in the volume of a single filling of the active mass on the oxide multimetallic) should be increased according to the invention expediently, at least 5 wt.%, preferably, at least 10 wt.% (this is true in particular when a single catalyst molded products across the fixed catalyst layer 3). Typically, this increase with the method according to the invention is not more than 50 wt.%, in most cases, not more than 40 wt.%. Further, when a single active mass around the fixed catalyst layer 3, the difference in specific volume of the active mass of the catalyst zone fixed layer with the lowest specific volume activity and zone of the fixed catalyst layer with the higher specific volume of activity should not be more than 50 wt.%, preferably not more than 40 wt.% and especially preferably not more than 30 wt.%. Often, when the method according to izopet is the fixed catalyst layer 3 consists of only two zones fixed catalyst layer.

According to the invention is preferably in the flow direction of the reaction gas mixture 3 is the last area of the fixed catalyst layer 3 is undiluted. This means that it is preferably entirely of catalyst molding. If necessary, it may consist of filling of the catalyst molded products, specific volume activity of which is reduced, for example, by dilution with an inert material, for example, 10%. If fixed catalyst layer 3 consists of only two zones fixed catalyst layer, according to the invention preferably in the General form according to the invention), if the area of the fixed catalyst layer with the higher specific volume of activity is in the temperature zone (in particular if the temperature zone C and in the temperature zone D exercise thermoregulation fluid coolant, which flows in countercurrent to the reaction gas mixture 3).

If fixed catalyst layer 3 consists of three zones, according to the invention, preferably, if the area of the fixed catalyst layer with the higher specific volume of activity is in the temperature zone (in particular if the temperature zone C and in the temperature zone D tempering fluid is those what lonavala, which flows in countercurrent to the reaction gas mixture 3).

If fixed catalyst layer 3 consists of four zones of the fixed catalyst layer, according to the invention, preferably, if the area of the fixed catalyst layer with the second largest highest specific volume of activity is in the temperature zone, and in the temperature zone D (especially when in the temperature zone C and in the temperature zone D tempering fluid is a coolant, which flows in countercurrent to the reaction gas mixture 3).

In the case of the supply of the reaction gas mixture 3 in parallel with the fluids in the temperature zones C and D according to the invention may be preferred if the catalyst inside the fixed layer 3 area with the highest specific volume activity is not included in the temperature zone, and has its origin behind the transition temperature zone in the temperature zone D. the Specific volume of activity between the two zones fixed catalyst layer within the fixed catalyst layer 3 can be determined experimentally in a simple way due to the fact that at the identical framework conditions, preferably conditions of the proposed method) at fixed catalyst layers of the same length, but according to the composition for the ment zone fixed catalyst layer, served the same containing acrolein reaction gas mixture. Most transformed number of acrolein shows the highest specific volume activity.

If the total length of the fixed catalyst layer 3 is L2according to the invention, preferably, if the rangeaccordingly, in the rangeaccordingly, in the rangeis not the transition from one zone fixed catalyst layer to another zone, and X is a place within the fixed catalyst layer 3, which is the transition temperature zone in the temperature zone D.

Preferably in the above method fixed catalyst layer 3 is structured in the direction of flow of the reaction gas mixture 3 is as follows.

First, in length from 10 to 60%, preferably from 10 to 50%, particularly preferably from 20 to 40% and more preferably from 25 to 35% (i.e., for example, the length of from 0.70 to 1.50 m, preferably from 0.90 to 1.20 m), the total length of the fixed catalyst layer 3, a homogeneous mixture or two (with decreasing dilution) consecutive mixture of the catalyst molded and molded-thinners (both basically have the same geometric shape), p is ICEM share molded products thinners measured so what specific volume of activity, in terms consisting only of the catalyst molded filling, reduced by 10 to 50 wt.%, preferably 20 to 45 wt.% and particularly preferably 25 to 35 wt.%. At the end of this first, respectively, both of these areas are to the end of the length of the fixed catalyst layer 3 (i.e., for example, the length of from 2.00 to 3.00 m, preferably from 2.50 to 3.00 m), or diluted only in a small volume (than in the first, respectively, in the first two zones) backfilling catalyst molded product, or, especially preferably, one covering the same catalyst molded products that have been applied in the first zones.

The above really especially when it is in a fixed catalyst layer 3 as a catalyst molded product applied ring solid catalysts or beads shell catalysts (in particular, those listed in this description as the preferred). With the advantage within the above structure as a catalyst molded product, respectively, their media, and the molded product is thinner in the method according to the invention are mainly geometric shape of rings with dimensions of 7 mm × 3 mm × 4 mm (external diameter × length × internal diameter).

The above is valid then when, instead of inert molded-thinners applied molded products shell catalyst, the proportion of active mass which is 2 to 15 wt.% lower than the proportion of the active mass of the molded shell of the catalyst at the end of the fixed catalyst layer 3.

Backfilling layer of pure inert material, the length of which in terms of the length of the fixed catalyst layer 3 mainly from 5 to 20%, preceded by a fixed catalyst layer in the flow direction of the reaction gas mixture 3. It is used for heating the reaction gas mixture 3. Instead of filling of inert material as the heating zone can also be used diluted with an inert material catalyst filling.

According to the invention preferably when called fixed catalyst layers 3 temperature zone (which extends also to the pre-filling of inert material) stretches for 5 to 20%, often 5 to 15% of the length of the latter in the direction of flow of the reaction gas mixture 3 (the most active specific volume) zone fixed catalyst layer 3.

An expedient manner on the technique of application of the second reaction stage of the described method is carried out in a two-zone shell-and-tube reactor as described, for example, in documents DE-A's 9910508, 19948523, 19910506 and 19948241. The preferred option is used according to the invention two-zone shell-and-tube reactor is disclosed in DE-C 2830765. However, DE-C 2513405, US-A 3147084, DE-A 2201528, EP-A 383224 and DE-A 2903218 describe suitable two-zone shell-and-tube reactors for carrying out the second reaction zone of the method described above.

This means that in the simplest case, the applicable fixed catalyst layer 2 a (possibly located before and/or after the inert backfill) is a metal tube shell-and-tube reactor and around the metal tubes are directed mostly separated from each other in space thermal environment, generally salt melts. A section of pipe, which extends the corresponding salt bath is a temperature zone according to the invention. This means that in the simplest case, for example, a salt bath And wrap around that part of the tubes (temperature zone a)in which the oxidative conversion of propene (in single pass) until a conversion in the range from 40 to 80% values UPseek according to the invention in a second reaction stage, and a salt bath In which surrounds the section of the tubes (the reaction zone), which is the final oxidative conversion of propene (in single pass) on the achievement of conversion in the range from 40 to 80% values U Pseek according to the invention in the second reaction stage (if necessary, to be applied according to the invention the temperature zones a, b can join other reaction zones which are kept at individual temperatures).

Regarding application techniques appropriate is that described in the second reaction stage does not include any other temperature zones. This means that the salt bath flows In an expedient manner a section of pipe, which is the final oxidative conversion of propene (in single pass) up to the value of UPseek according to the invention.

Usually the start temperature zone is behind the maximum hot spot temperature zone A.

Both salt bath And, according to the invention can be directed against the direction of flow of the reaction gas mixture in a co-current or counter-current through surrounding the reaction tube space. Needless to say, in the temperature zone a may be parallel and in the temperature zone In counterflow (or Vice versa).

Needless to say, in all the above cases, it is possible within each temperature zone occurred relative to the reaction tubes parallel to the flow of salt solution still apply transverse p is the current so that the individual reaction zone corresponds described in EP-A 700714 or in EP-A 700893 shell-and-tube reactor, and in General in longitudinal section through the beam contact tubes resulting flow in the form of a meander.

An expedient manner described method, the reaction gas source mix 2 is fed to the fixed catalyst layer 2, preheated to the reaction temperature.

Usually in two-phase shell-and-tube reactor of the contact tube is made of ferrite steel and have a wall thickness of from 1 to 3 mm, its inner diameter is generally from 20 to 30 mm, frequently from 21 to 26 mm in length an expedient manner is from 2 to 4 m, preferably from 2.5 to 3.5 m In each temperature zone backfill fixed catalyst layer is at least 60%, at least 75%or at least 90% of the length of the zone. The remaining, if necessary, the length of loaded, if necessary, an inert filling. From the point of view of technology use is appropriate, such execution, which is placed in the vessel shell-and-tube reactor, the number of contact tubes is, at least, from 15,000 to 30,000. Shell-and-tube reactors with lying above 40000 number of contact tubes form the exception. Inside capacity of the contact tube in the normal SL the tea homogeneous distributed (preferably 6 equally-spaced adjacent pipe on one contact tube), moreover, the distribution is chosen so that the distance of the Central internal axes lying closer to each other contact tubes (the so-called division of the contact tubes) is from 35 to 45 m (see, for example, the document EP-468290).

As the heat transfer agent is also suitable for two-phase mode liquid tempering medium. Especially preferably the use of melts of salts such as potassium nitrate, potassium nitrite, sodium nitrite and/or sodium nitrate, or viscoplastic metals such as sodium, mercury and alloys of different metals.

As a rule, in all the above cases, logging two-phase flow in shell-and-tube reactors, the flow rate inside both required circulation paths of heat transfer agent is selected so that the temperature of the heat transfer agent from the point of entry into the temperature zone to the exit temperature zones (due to ectodermal reaction) increases by 0 to 15°C. This means that the above temperature may range according to the invention from 1 to 10°C., or from 2 to 8°C., or from 3 to 6°C.

The inlet temperature of the heat transfer agent in the temperature zone And is usually according to the invention from 290 to 380°C., preferably from 305 to 365°C. and particularly preferably from 310 to 340°C, respectively, 330°C. Under a load of propene catalyst is aqueous stationary layer 2 ≥90 nl/l·h and ≤ 160 nl/l·h inlet temperature of heat transfer agent in the temperature zone according to the invention is from 290 to 380°C, at the same time usually according to the invention ≥ 0°C to ≤ 20°C or ≤ 10°C, respectively, ≥ 0°C and ≤ 5°C or often ≥ 0°C and ≤ 3°C below the input temperature in the temperature of the incoming area And heat transfer agent. When the load propene catalyst fixed layer 2 ≥160 nl/l·h and (usually) ≤ 300 nl/l·h (respectively 600 nl/l·h) inlet temperature of heat transfer agent in the temperature zone according to the invention is from 290 to 380°C or usually according to the invention ≥ 0°C to ≤ 50°C or ≥ 5°C and ≤ 45°C or ≥ 10°C and ≤ 40°C or ≥ 15°C and ≤ 30°C or ≤35°C (e.g., 20°C or 25°C) higher than the input temperature in the temperature of the incoming area And heat transfer agent.

You should indicate that to conduct the reaction stage 2 of the method according to the invention can be applied are described in DE-AS 2201528 two-phase shell-and-tube reactor, which has the ability to divert from the hot heat transfer agent temperature zone At a partial number on the temperature zone And, if necessary, to influence the heating of cold reactive gas source of a mixture of 2 or cold circulating gas. Further characteristics of the shell-and-tube reactor can be made in the individual temperature zones, as described in document EP-A 382098.

The rest is advisable to cool pokey is surrounding the second reaction stage product gas mixture 2 in front of the entrance to the third reaction stage directly and/or indirectly, in order to suppress the subsequent complete combustion parts formed in the second stage of acrolein. Typically this is between the two reaction stages is included subsequent cooler. They can be in the simplest case, indirect shell-and-tube heat exchanger. The product gas mixture 2 in this case, as a rule, goes through the pipe and around the pipe heat exchanger is directed environment where you can meet recommended for shell-and-tube reactor heat exchange medium. Mostly inner tube filled with inert fillers (e.g., spirals of stainless steel, rings of steatite, beads of steatite and so on). They improve the heat transfer and, if necessary, catch sublimating of the fixed catalyst layer 2 of the second reaction stage, the molybdenum trioxide before it is input to the third reaction stage. The advantage of this embodiment in which the subsequent cooler is made of stainless steel coated with a paint based on a silicate of zinc.

Rezultirase in a single pass in the second reaction stage, the selectivity of the formation of acrolein and formation of by-product acrylic acid according to the invention is ≥ 92 mol.% or ≥ 94 mol.%, often ≥ 95 mol.% or ≥ 96 mol.%, accordingly, ≥ 97 mol.%.

Consider what Ino application techniques suitable way of product gas mixture 2 second reaction stage is cooled in the already mentioned subsequent cooling to a temperature of from 210 to 290°C, often from 230 to 280°C. or from 250 to 270°C. While cooling the product gas mixture 2 second reaction stage carried out to a temperature which lies below the temperature of the third reaction stage. Described subsequent cooling in any case not enforced, and can then fall away when the path is the product of the reaction mixture 2 from the second reaction stage in a third reaction stage is kept short. Preferably, the method of two-stage partial oxidation is carried out in such a way that the oxygen demand in the third reaction stage is not covered already correspondingly high oxygen content of the reaction gas source mixture 2, and the required oxygen is added to the second area and the third reaction stage (secondary additive oxygen"). This can be done before, during, after and/or subsequent cooling. The source is required for the third reaction stage of molecular oxygen is suitable both pure oxygen and mixtures of oxygen and inert gas, for example air (preferred according to the invention) or depleted molecular oxygen (for example, ≥ 90% vol. O2, ≤ 10% vol. N2). Additive source of oxygen is regularly compressed to the pressure of the reaction form. Needless to say that with the method according to image the structure of the oxygen demand in the second reaction stage may be covered already by the corresponding high oxygen demand in the second reaction stage. Of course if needs as secondary gas may be added inert gas diluent.

As the second reaction stage, the third reaction stage is carried out by the method according to the invention expediently in the two-stage shell-and-tube reactor, already described for the second reaction stage, performance relative to the two-stage shell-and-tube reactor for the second reaction stage is valid for two-phase shell-and-tube reactor for the third reaction stage.

This means that a simple way used according to the invention fixed catalyst layer 3 (if necessary, including filling of inert material) is in a metal tube shell-and-tube reactor, and around metal pipes are routed two separated from each other in the space of a tempering medium, generally salt melts. Cut pipe, which extends the corresponding salt bath is a temperature zone according to the invention.

This means that a simple way, for example, a salt bath With wrap around that part of the tubes (temperature zone)in which the oxidative conversion of acrolein (in one pass) to reach the value of the conversion in the range from 45 to 85%, predpochtitel is about 50 to 85%, particularly preferably from 60 to 85% of the value UAseek in the third reaction stage according to the invention, and a salt bath D which surrounds the section of the tubes (temperature zone D, which is the final oxidative transformation of acrolein (in a single pass) until a conversion UA(if needs to be applied according to the invention the temperature zones C, D can still connect other temperature zones which are kept at individual temperatures).

According to the technique of applying an expedient manner reactionary stage 3 of the method according to the invention does not include other temperature zones. This means that a salt bath D flows around an expedient manner a section of pipe in which the oxidative conversion of acrolein (in one pass) to the value UAseek according to the invention.

Usually the start temperature zone D is located behind the maximum hot spot temperature zone C.

Both salt bath C, D according to the invention can be made relative to the direction of current flow in the reaction tube, the reaction gas original mix 3 in a co-current or counter-current in the surrounding reaction tubes of the space. Needless to say, according to the invention in the temperature zone may, at enetica bypass and in the temperature zone D counterflow (or Vice versa).

Needless to say, in all cases of execution within each temperature zone occurred relative to the reaction tubes parallel to the flow of saline solution is still to impose cross-thread, so that the individual reaction zone corresponds described in EP-A 700714 or in EP-A 700893 shell-and-tube reactor, and in General in longitudinal section through the beam contact tubes resulting flow in the form of a meander.

Typically, in the above two-stage shell-and-tube reactor for the third reaction zone of the contact tube is made of ferrite steel and have a typical thickness of 1 to 3 mm, its inner diameter is generally from 20 to 30 mm, frequently from 21 to 26 mm in length an expedient manner is from 2 to 4 m, preferably from 2.5 to 3.5 m In each temperature zone backfill fixed catalyst layer is at least 60%, at least 75%or at least 90% of the length of the zone. The remaining, if necessary, the length of loaded, if necessary, an inert filling. From the point of view of technology use is appropriate, such execution, which is placed in the vessel shell-and-tube reactor, the number of contact tubes is, at least, from 15,000 to 30,000. Shell-and-tube reactors with lying above 40000 number to intaktnykh pipes form the exception. Inside capacity of the contact tube in the normal case distributed homogeneous (preferably 6 equally-spaced adjacent pipe on one contact tube), and the distribution is chosen so that the distance of the Central internal axes lying closer to each other contact tubes (the so-called division of the contact tubes) is from 35 to 45 m (see, for example, the document EP-468290).

As the heat transfer agent is suitable, in particular, liquid tempering medium. Especially preferably the use of melts of salts such as potassium nitrate, potassium nitrite, sodium nitrite and/or sodium nitrate, or viscoplastic metals such as sodium, mercury and alloys of different metals.

As a rule, in all the above cases, logging two-phase flow in shell-and-tube reactors of the third reaction stage, the flow velocity inside both required circulation paths of heat transfer agent is selected so that the temperature of the heat transfer agent from the point of entry into the temperature zone to the exit temperature of the zone is increased by 0 to 15°C. This means that the above temperature may range according to the invention from 1 to 10°C., or from 2 to 8°C., or from 3 to 6°C.

The inlet temperature of the heat transfer agent in the temperature zone is usually according to the invention from 230 to 320°C, p is edocfile from 250 to 300°C. and particularly preferably from 260 to 280°C. When the load acrolein fixed catalyst layer 3 constituting ≥ 70 nl/l·h and ≤ 150 nl/l·h, the inlet temperature of the heat transfer agent in the temperature zone D according to the invention is from 230 to 320°C, while usually according to the invention ≥ 0°C to ≤ 20°C or ≤ 10°C, respectively, ≥ 0°C and ≤ 5°C or often ≥ 0°C and ≤ 3°C below the input temperature of the incoming in the temperature zone With a heat transfer agent. When the load acrolein fixed catalyst 3, the components of ≥ 150 nl/l·h and (usually) ≤ 300 nl/l·h (respectively, 600 nl/l·h), the inlet temperature of the heat transfer agent in the temperature zone D according to the invention is from 230 to 320°C, or usually according to the invention ≥ 0°C to ≤ 40°C or ≥ 5°C and ≤ 35°C 30°C or ≥ 10°C and ≤ 25°C, respectively 20°C or 15°C above the inlet temperature of the incoming in the temperature zone With a heat exchange agent.

You should indicate that to conduct the reaction stage 3 of the method according to the invention can be applied are described in DE-AS 2201528 two-phase shell-and-tube reactor, which has the ability to divert from the hot heat transfer agent temperature zone D partial number on the temperature zone, so that, if necessary, to influence the heating of the cold reaction gas original mix 3 or cold C is relacionado gas. Further characteristics of the shell-and-tube reactor can be made in the individual temperature zones as described in the document EP-A 382098.

Needless to say, for the third reaction stage of the method according to the invention can be applied also described in the document DE-AS 2201528 type shell-and-tube reactor, which has the ability to divert from the hot heat transfer agent temperature zone D partial amount to the reaction zone so that, if necessary, to affect the heat too cold reaction gas original mix 3. Further characteristics of the shell-and-tube reactor inside the individual reaction zones can be performed as described in document EP-A 382098.

Needless to say, for carrying out the method according to the invention two stage shell-and-tube reactor can be included in one chetyrehstoronny shell-and-tube reactor as described in document WO 01/36364. Usually in these cases between the fixed catalyst layer 2 and the fixed catalyst layer 3 is inert filling. However, this filling can also be abandoned. The length of the reaction tubes corresponds in the case of a merger of shell-and-tube reactors, the amount of unmerged shell-and-tube reactors.

At this point it should be noted that as for catalyst NEPAD is mportant layer 2, and for the fixed catalyst layer 3 is also suitable active mass on the metal oxides from the document DE-A 10261186.

Favorable execution of two-phase shell-and-tube reactor for the second reaction stage may be as follows (constructive can be in applications for industrial designs 20219277.6, 200219278.4 and 20219279.2, respectively, in PCT applications PCT/ER/14187, PCT/ER/14188 or PCT/ER/14189):

contact pipe:

material contact tube: ferrite steel;

the dimensions of the contact tubes: for example, 3500 mm length; for example, 30 mm outer diameter; for example, 2 m wall thickness;

the number of contact tubes in the tube bundle: for example, 30000, or 28000, or 32000, or 34000; optional up to 10 thermotron (as described in EP-A 873783 and EP-A 1270065), which is loaded as the contact tube (spiral from outside to inside), for example, of the same length and wall thickness, but with an external diameter of, for example, 33,4 mm and centered thermogenesis, for example, 10 m external diameter and, for example, 1 mm wall thickness;

the reactor (material as the contact tube):

cylindrical container with an inner diameter of 6000-8000 mm;

the cap of the reactor is lined with plates of precious metal type 1,4541; plate thickness: several mm;

located koltseobrazno tube bundle, for example, with a free Central chamber;

the diameter of the Central free camera,for example, 1000-2500 mm (for example, 1200 mm 1400 mm 1600 mm 1800 mm 2000 mm 2200 mm 2400 mm);

usually homogeneous distribution of the contact tubes in the tube bundle (6 equidistant adjacent pipe on one contact tube), the location in the right triangle,

the distribution of the contact tube distance of the Central internal axes lying closest to each other pipes): 35-45 mm, for example, 36 mm, 38 mm or 40 mm or 42 mm or 44 mm;

the contact tube is hermetically secured with their ends to the bottoms of the contact tube (upper plate and the lower plate, for example, with a thickness of 100-200 mm) and at their upper ends end connected with the container cap, which has an inlet for the reaction gas source mixture 2; are, for example, half the length of the contact tube separating the sheet from 20-100 mm separates the reactor symmetrically into two temperature zones (upper zone) and (lower zone); each temperature zone is divided deflecting pucks into two equally-spaced segment;

deflecting the washer preferably has an annular form; contact tube fixed tightly on the separating sheet; deflecting the puck they fixed negerlein, so that the speed of the cross flow salt bath within a zone as possible const;

each zone is supplied by its own salt n is Sosa salt melt as the heat transfer medium; feeding molten salt, for example, deflecting the puck and selection on top of the deflector washer;

both cycles molten salt is withdrawn, for example, a partial stream and, for example, is cooled in one common or two separate indirect heat exchangers (steam);

in the first case, the cooled stream of molten salt is separated, combined with a residual stream and using the appropriate pump is blown into the corresponding annular channel, which distributes the molten salt by volume capacity, and in the reactor;

after being on the cover of the reactor window molten salt enters the tube bundle;

the flow into is, for example, in the radial direction of the tube bundle;

molten salt flows in each zone, following deflecting the sheet, for example, in the following order

- from outside to inside,

- from the inside out,

- around the contact tubes;

via placed around the circumference of the vessel window molten salt is collected on each end of the zone located around the casing of the reactor annular channel, and then to be introduced to cool the partial flow in the loop;

through each temperature zone of the salt melt is fed from the bottom up.

The reaction gas mixture leaves the reactor of the second reaction stage at a temperature a few degrees higher than the inlet temperature of alevai bath reactor. The reaction gas mixture for further processing expedient manner is cooled in a separate subsequent cooler, which is connected with the reactor of the second reaction stage, to a temperature of from 220°C to 280°C, preferably from 240°C to 260°C.

Subsequent cooler, as a rule, fixed flanges under the lower bottom of the pipe and usually consists of pipes made of ferrite steel. In the subsequent pipe cooler inside the entered sheet spiral of stainless steel, which can be partially or completely twisted to improve the heat transfer.

Molten salt:

as the molten salt may be used a mixture of 53 wt.% potassium nitrate, 40% wt. sodium nitrate, 40% wt. sodium nitrite and 7% wt. sodium nitrate; both the reaction zone and subsequent cooler used with the advantage of molten salt with the same composition; injected into the reaction zone, the amount of salt can be on an area of approx. 10000 m3/PM

Flow direction:

the reaction gas source mix 2 flows expedient way down through the two-stage reactor, while different temperarure salt melts separate areas served expedient way from the bottom up;

download contact tubes and thermatru (top to bottom), for example:

section 1:50 cm long
rings made of steatite with form 7 mm × 7 mm × 4 mm (external diameter × length × internal diameter) as a pre-backfill
segment 2:140 cm
catalyst loading homogeneous mixture of 20 wt.% rings made of steatite with the shape of 5 mm × 3 mm × 2 mm (external diameter × length × internal diameter) and 80 wt.% the solid catalyst of segment 3 (alternative, you can apply a homogeneous mixture of only 70 wt.% the solid catalyst of the segment 3 and 30 wt.% the above rings from steatite)
segment 3:160 cm long
download the catalyst with an annular (5 mm × 3 mm × 2 mm = external diameter × length × internal diameter) solid catalyst according to example 1 of document DE-A 10046957 (stoichiometry: [Bi2W2O9×2WO3]0,5[Mo12Co5,5Fe2,94Si1,59K0,08Ox]1)

Favorable execution of two-phase shell-and-tube reactor for the third reaction stage may be as follows:

all, as in the two-stage shell is rubem the reactor for the second reaction stage. The thickness of the top and bottom of the bottom contact of the pipes is often 100-200 mm, for example, 110 mm or 130 mm or 150 mm or 170 mm or 190 mm

Subsequent cooler is eliminated; instead, the contact tube includes its bottom hole connected to the lower end of the tank cap with the release of the product gas mixture; the upper temperature zone is, and the lower temperature zone is the temperature zone d Between the output of the future "cooler" and the entrance to the reactor for the third reaction stage has a reasonable manner the ability to supply compressed air.

Download contact tubes and thermotron may be, for example, as follows (top to bottom):

section 1:20 cm long
rings made of steatite with the geometry 7 mm × 7 mm × 4 mm (external diameter × length × internal diameter) as a pre-backfill
segment 2:90 cm long
catalyst loading homogeneous mixture of 20 wt.% steatite rings with the geometry 7 mm × 3 mm × 4 mm (external diameter × length × internal diameter is ETP) and 80 wt.% shell catalyst of segment 4 (alternative can be applied homogeneous mixture of 70 wt.% shell catalyst of the segment 4 and 30 wt.% the above steatite rings)
segment 3:50 cm long
catalyst loading homogeneous mixture of 15 wt.% steatite rings with the geometry 7 mm × 3 mm × 4 mm (external diameter × length × internal diameter) and 85 wt.% shell catalyst of segment 4 (alternative can be applied homogeneous mixture of 70 wt.% shell catalyst of the segment 4 and 20 wt.% the above steatite rings)
segment 4:190 cm in length
catalyst loading of annular (7 mm × 3 mm × 4 mm = external diameter × length × internal diameter) shell catalyst according to exemplary embodiment 5 of the document DE-A 10046928 (stoichiometry: Mo12V3W1,2Cu2,4Ox)

Download contact tubes and thermotron third stage may look as follows (top to bottom):

section 1:20 cm long
steatite rings with the geometry 7 mm × 7 mm × 4 mm (external diameter × length × internal diameter) as a pre-Clos is Ki
segment 2:140 cm
catalyst loading homogeneous mixture of 20 wt.% steatite rings with the geometry 7 mm × 3 mm × 4 mm (external diameter × length × internal diameter) and 80 wt.% shell catalyst of segment 3 (alternative can be applied homogeneous mixture of 75 wt.% shell catalyst of the segment 3 and 25 wt.% the above steatite rings)
segment 3:190 cm in length
catalyst loading of annular (7 mm × 3 mm × 4 mm = external diameter × length × internal diameter) shell catalyst according to exemplary embodiment 5 of the document DE-A 10046928 (stoichiometry: Mo12V3W1,2Cu2,4Ox)

In the above-mentioned two-stage load shell-and-tube reactor, the solid catalyst of example 1 of document DE-A 10046957 can also be replaced by the following:

a) the catalyst according to example 1C from the document EP-A 15565, or made according to this example, the catalyst has an active mass Mo12Ni6,5Zn2Fe2Bi1P0,0065K0,06Ox·10SiO2;

b) sample Nr. 3 from the document DE-A 19855913 in image quality is as a catalyst to form a hollow cylinder with geometry 5 mm × 3 mm × 2 mm, accordingly, 5 mm × 2 mm × 2 mm;

c) a solid catalyst based on oxide multimetallic II according to example 1 of document DE-A 19746210;

d) shell catalysts 1, 2 and 3 from the document DE-A 10063162, but with the same thickness of the shell is marked on the ring-bearers with geometry 5 mm × 3 mm × 1.5 mm, respectively, 7 mm × 3 mm × 1.5 mm;

e) catalysts, in particular examples of implementation of the documents DE-A 10344149 and DE-A 10353954.

All the above downloads the third reaction stage shell catalyst according to exemplary embodiment 5 of the document DE-A 10046928 can be replaced with:

a) shell catalyst S1 or S7 from DE-A 4442346 with a share of active mass 27 wt.%, the shell thickness of 230 μm;

b) shell catalyst according to examples 1 to 5 of the document DE-A 19815281, however, marked on ring geometry 7 mm × 3 mm × 4 mm with a share of active mass to 20 wt.%;

(C) shell catalyst with a two-phase active mass with the stoichiometry (Mo10,4V3W1,2Ox)(CuMo0,5W0,5O4)1,6obtained according to DE-A 19736105, and with the share of active mass to 20 wt.%, supported on a carrier with the geometry 7 mm × 3 mm × 4 mm

In the rest of the fixed catalyst layer 2 and the fixed catalyst layer 3 are selected according to the invention thus (for example, dilution with inert material is m), the temperature difference between the maximum hot spot of the reaction gas mixture in a separate reaction zone and the temperature of the reaction zone generally does not exceed 80°C. In most cases, this temperature difference is 70°C, often it lies at 20 to 70°C. preferably, this temperature difference is minimal. In addition, the fixed catalyst layers for security reasons known to a person skilled way chosen (for example, by dilution, for example, inert material)that "peak-to-salt temperature sensitivity" is defined in the document EP-A 1106598 is ≤ 9°C or ≤ 7°C or ≤ 5°C or ≤ 3°C.

Subsequent cooler and the reactor for the third reaction stage are connected to the connecting pipe, the length of which is less than 25 meters

In the above described manner of connecting the reactor to the third reaction stage ring-shaped molded product is thinner and the annular catalyst molded product can also be replaced by a spherical molded products-diluents and the annular catalyst molded products (each with a radius of 2 to 5 mm and the proportion of active mass from 10 to 30 wt.%, often from 10 to 20 wt.%).

Leaving the method according to the invention after the third reaction stage product gas mixture 3, as a rule, mainly composed of zelenog the product of acrylic acid, unreacted molecular oxygen (relative to the lifetime of the applied catalysts favorable, if the oxygen content in the product gas mixture 3 is still less than 1.5 to 4 vol.%), propane, unreacted propylene, molecular oxygen, formed as a by-product and/or used as the diluent gas water vapor as a by-product and/or used as the diluent gas carbon oxides and small amounts of other lower aldehydes, lower alkenylboronic acids (e.g. acetic acid, formic acid and propionic acid)and maleic anhydride, benzaldehyde, aromatic carboxylic acids and aromatic anhydrides of carboxylic acids (e.g., anhydride talavou acid and benzoic acid), if necessary, other hydrocarbons, such as With4-hydrocarbons (e.g., butene-1 and possibly other butenes) and other inert gaseous diluents.

The target product can be separated from the product gas mixture 3 in a known manner in the separation zone (e.g., partial or full, and if necessary fractionated condensation of acrylic acid or absorption of acrylic acid in water or in high-boiling hydrophobic organic solvent, and that the same processing condensate and/or absorbate, according to the invention preferably the product gas mixture 3 is subjected to fractionated condensation; see, for example, the document EP-A 1388533, EP-A 1388532, DE-A 10235847, EP-A 792867, WO 98/01415, EP-A 1015411, EP-A 1015410, WO 99/50219, WO 00/53560, WO 02/09839, DE-AND 10235847, WO 03/041833, DE-A 10223058, DE-A 10243625, DE-A 10336386, EP-A 854129, US-A 4317926, DE-A 19837520, DE-A 19606877 DE-A 190501325, DE-A 10247240, DE-A 19740253, EP-A 695736, EP-A 982287, EP-A 1041062, EP-A 117146, DE-A 4308087, DE-A 4335172, DE-A 4436243, DE-AND 19924532, DE-A 10332758, and also DE-A 19924533). Department of acrylic acid can be carried out as described in documents EP-A 982287, EP-A 982289, DE-A 10336386, DE-A 10115277, DE-A 19606877, DE-A 19740252, DE-A 19627847, EP-A 920408, EP-A 1068174, EP-A 1066239, EP-A 1066240, WO 00/53560, WO 00/53561, DE-A 10053086 and EP-A 982288. Preferably the separation is carried out, as described in figure 7 of document WO/0196271, respectively, in the document DE-A 102004032129 and equivalent documents. Favorable method of separation described in WO 2004/063138, WO 2004/035514, DE-A 10243625 and DE-A 10235847. Further processing of the resulting crude acrylic acid can be carried out, as described in documents WO 01/77056, WO 03/041832, WO 02/055469, WO 03/078378 and WO 03/041833.

A common feature of these methods of separation is that (as already mentioned)that in the upper part containing effective for the separation nozzle separation column, the lower part of which is usually supplied in the product gas mixture 3, in the normal case, after her previous direct and/or indirect about what ladenia, remain in the normal case are those components of the product gas mixture 3, the boiling point of which at normal pressure (1 bar) is ≤ -30°C (i.e. tyazheloranennaya or volatile components).

In the lower part of the separation columns usually have tielaechi components of the product gas mixture 3, including the target product of acrylic acid in the condensed phase.

The components of the residual gas are primarily propane, unreacted during partial oxidation of propylene, molecular oxygen, and is often used in partial oxidation, an inert gas diluent such as nitrogen and carbon dioxide. Water vapor may be contained in the residual gas, depending on the applied method of separation only in trace amounts or in amounts up to 20% vol. or more.

Contained in the residual gas, propane and propylene according to the invention are recirculated, as already described.

During the processing of the condensed phase for separation of the target product) may be formed of other residual gases, as according to the invention preferably are trying to recycle in General contained in the product gas mixture 3, respectively, 2 the amount of unreacted propane and propylene in the first reaction stage (for example, Goethe is ogendo catalyzed dehydrogenation of propane and/or oxidisation propane), they contain, as a rule, propane, and propylene, but more often do not contain molecular oxygen. Usually they are combined with the main residual gas in the total residual gas and are recirculated to the first reaction stage (for example, heterogeneous catalyzed dehydrogenation of propane and/or oxidisation propane). However, it is also possible to separate the recycling of these residual gases, for example, on the second and/or third reaction stage.

Due to the preferably complete recycling of the remaining propane and propylene can be carried out in a continuous mode continuous conversion of propane to acrylic acid.

Essential according to the invention is that due to the described recirculated to the first reaction stage on it despite the limited conversion of propylene in the reaction stage 2 General method may be achieved by the transfer of propane to propylene with almost complete selectivity.

The advantages of this method are also available at as low (≤ 30 mol.%), and high (≥ 30 mol.%) the conversion of the dehydrogenation (in terms of disposable passage of fresh propane through dehydration). In General, when such recirculation circulating gas oxidation beneficial if the content of hydrogen in the reaction gas source mixture 1 is the, at least the stoichiometric ratio (relative to combustion oxygen to the water to recycled through the circulation gas oxidation in the reaction gas source a mixture of 1 volume of oxygen.

Circulation according to the invention, the mode is applicable when the partial oxidation is a partial amoicillin of propene to Acrylonitrile. It is applicable also when the dehydrogenation of propane is replaced with ISO-butane and resultwise while ISO-butane relevant, the partially oxidized at a stage of partial oxidation in methacrolein and/or methacrylic acid.

The advantage of the method according to the invention is, in principle, that in all places of the present description, including examples, where describes diluted with an inert material loading catalyst, appropriate catalysts for the same length of the layer can also be applied undiluted.

It should be pointed out again that the separation of the acrylic acid obtained according to the invention the product gas mixture 3 (in particular, from the product gas mixture 3 of the exemplary embodiment of the present description) is carried out preferably so that, if necessary, through direct and/or indirect cooling of the cooled product gas with the ect 3 fraktsionirovannoe condense in containing effective for separation of the nozzle column in a side drainage of crude acrylic acid with Slobodyanik and/or by means of water and/or aqueous solution absorb, as described in WO 2004/035514 and DE-A 10243625. Selected crude acrylic acid is preferably subjected to further suspension crystallization, and the resulting suspension crystallized acrylic acid is separated using the scrubber from the remaining mother lye. With the advantage of the washing liquid is applied to the melt pre-separated in the scrubber crystals of acrylic acid. Further, the scrubber is preferably scrubber with forced transport layer crystals. Especially preferably it comes to hydraulic or mechanical scrubber. In case you can follow the description of the documents WO 01/77056, WO 03/041832 and WO 03/041833. This means that the remaining mother lye is recycled by fractionated condensation (cf. also EP-A 1015410). The release side components is usually located under the side-wall of the crude acrylic acid. When using only one stage of crystallization get acrylic acid with purity 99.8 wt.%, fit great way to get superabsorbers on the basis of poly-Na-acrylate.

Examples (all pressure and constantly in this description represent absolute pressure, if nothing else is stated)

A) Performing the reaction stage 1 (stage dehydrogenation)

Stage degidio the project consists of three connected one after another identical tubular reactors, are identically loaded catalyst for dehydrogenation.

A separate tubular reactor is a steel pipe (stainless steel DIN material no. 1.4841) with a length of 1300 mm, wall thickness of 3.6 mm and an inner diameter 53,1 mm Tubular reactors are streamed reaction gas mixture 1 from top to bottom.

At the lower end of the tubular reactor is the carrier bars of the same stainless steel. On the carrier grating is bottom-up the next boot:

175 mm length backfill of steatite beads (diameter 4-5 mm) of steatite C-220 CeramTec;

21 mm length backfill layer of steatite beads (diameter 1.5-2.5 mm) of steatite C-220 CeramTec;

210 mm length backfill of dehydrogenation catalyst (Pt/Sn alloy, which promovieren elements Cs and La in oxidized form and printed on the external and internal surface of the ZrO2·SiO2molded from mixed oxide (average length (Gaussian distribution in the range from 3 mm to 12 mm with a maximum of about 6 mm): 6 mm, diameter: 2 mm) in the stoichiometry of the elements (mass ratio, including the media) Ptfor 0.3Snfor 0.6La3,0Cs0,5Kof 0.2(ZrO2)88,3(SiO2)7,1(getting the catalyst precursor is activated to an active catalyst, as in example 4 of the document DE-A 10219879).

21 mm length backfill of steatite beads (diameter 1, - 2.5 mm) of steatite C-220 CeramTec;

in conclusion, the residual length of the tubular reactor again backfilling of steatite beads (diameter 4-5 mm) of steatite C-220 CeramTec.

Each of the tubular reactors outside invested in the meaning of a segment of pre-heating on the first 500 mm length of pipe from the top down (to the carrier bars) in two ensure uniform distribution of the supplied amount of heat of poluchasa of copper (200 mm), which is electrically heated by the surrounding around the entire circumference of the heating cuff (firm Horst, DE-Heidelberg, 500 mm long, 100 mm inner diameter).

Bottom-up each tubular reactor in the sense of adiabatic cut lengths of 600 mm placed in two pairs of thermally solarwise existing pelucas (thickness 25 mm) from the MPS-Super G company Microtherm, DE, which are offset by 90° each other. Current solarwise poluchasa in turn surrounded by a cylindrical envelopes of stainless steel (outer diameter of 173 mm, inner diameter of 167 mm), to which is applied with the aim of accompanying the heating of the heating sleeve (length 675 mm, the inner diameter of 173 mm) firm Horst, DE-Heidelberg. Thus it is possible to minimize on the adiabatic segment the flow of heat from the environment into the reaction tube and the reaction tube to the outside in the environment.

In each reaction tube is introduced in the middle of the additive is about thermogels length 1370 mm (outer diameter: 6 mm, inner diameter: 4 mm), which introduced thermocouple (with the lower end of the reactor up every 4 cm a total of 10 measurement, thickness 3.2 mm).

Before each tubular reactor enabled filled steatite rings (steatite C-220 CeramTec and geometry 7 mm × 3 mm × 3 mm = external diameter × inner diameter × height) steel pipe with a length of 1300 mm as a heater. In her reaction gas source 1 mixture is pre-heated to the inlet temperature of the next tubular reactor and at the same time perfectly mixed. For this purpose, the heating pipes (stainless steel DIN number 1.4841, the wall thickness of 3.6 mm, inner diameter 53,1 mm) pipe length 1200 mm electrically heated by placing around them heating cuff firm Horst, DE-Heidelberg. The connection between the heater and tubular reactors performed using thermally insulated pipe of the noble metal (noble metal DIN number 1.4841, outer diameter 21.3 mm, inner diameter of 16.1 mm, length approx 700 mm).

Before entering the reaction gas source a mixture of 1 in the appropriate heater is the feed valve, through which the reaction gas mixture 1 is possible to bring the compressed air. The following describes the stationary mode.

To the first dehydrogenation reactor down the reaction gas iskhodno the mixture 1 of 300 g/h of crude propane (the first containing propane feed stream), 375 g/h of water and 3768 g/h total circulating gas With3(the second containing the (untransformed) propane (and unconverted propylene) the feed stream with a temperature of 400°C and a pressure of 2.6 abs. bar (in large technical scale input pressure is chosen at approx. 0.5 bar above to take into account an increased pressure loss (due to high flow velocities) in the reaction stage 1).

The crude propane contains:

vol.%
methane0
Ethan0,156
Eten0
propane96,18
propene (propylene)0,002
H20
About20
N21,70
CO0
CO20
ISO-butane1,245
n bout the n 0,711
TRANS-butene0,0005
ISO-butene0
CIS-butene0,0015
1-butene0,0048
butadiene0

General circulation3-gas contains:

n-butane
vol.%
methane0,009
Ethan0,088
Eten0,038
propane29,56
propene0,122
H20,050
O23,35
N264,05
CO0,538
CO21,85
ISO-butane0,234
0,098
TRANS-butene0,00005
ISO-butene0,00051
CIS-butene0,00144
1-butene0,00048
butadiene0,0087

The composition of the crude propane and other gas components perform gas chromatography [HP 6890 with Chem-Station, detectors: FID, WLD, separating columns: Al2O3/KCl - (Chrompack), Carboxen 1010 (Supelco)]. When containing water vapor gas mixtures prior to gas chromatographic analysis it is condensed by cooling and, if necessary, the negative pressure in the precipitator water. Unfused remaining gas is analyzed, and in terms of this calculated dry gas (i.e. contained in itself needs to be analyzed gas mixture, the amount of water vapor remains without consideration) given all of the data.

The reaction gas source mix 1 get in the evaporator, which is connected to the first heater. The evaporator itself is designed as a heater. To him serves 300 g/h of gaseous crude propane (65°C, 5 bar), 3768 g/h General circulation3gas (50°C, 2.8 bar) and 375 g/h of water (20°C, 3 bar). Heating of the evaporator of the regulation on the output temperature of the total mixture at 200°C. The evaporator is connected with the first heater accordingly, as the reactors associated with the evaporators.

Heating the first heater is adjusted so that it is fed from the evaporator in the first heater gas mixture leaving the first heater at a temperature of 400°C (required for this purpose, the wall temperature is approx. 440°C). Then the reaction gas source mixture fed to the first tubular reactor and the segment pre-heating of the reactor is heated to the inlet temperature of the reaction zone 460°C.

The temperature of the reaction gas mixture 1 when passing through the first tubular reactor is maximum (called the temperature of the hot spot) in 549,1°C (quantitative values are given here in terms of the state after 200 operating hours; in the further exploitation of other temperature carried out in such a way that the conversion in terms of disposable aisle and out in space and time remain essentially constant; accordingly received in the first 200 operating hours), during continuous operation of the test set due to the gradual deactivation of the catalyst is shifted in the direction of the flow (velocity offset is approx. 0.03 mm/h).

Leaving the first reactor for the dehydrogenation reaction of the gas with the feature 1 has the following composition:

vol.%
methane0,045
Ethan0,109
Eten0,042
propane30,3
propene2,88
H25,00
O20
N2$ 59.13 USD
CO0,06
CO23,24
ISO-butane0,257
n-butane0,116
TRANS-butene0,05
ISO-butene0,001
CIS-butene0,004
1-butene0,001
butadiene0,003

Her temperature which is 509°C, and its pressure is OK. 2,56 bar.

Before entering the next heater to the reaction gas mixture 1 serves 80 nl/h of compressed air (23°C, 4,2 bar).

Then the reaction gas mixture 1 is heated using an electric heating capabilities heater (wall temperature of around 540°C) and the length of pre-heating the next reaction tubes (second) (the wall temperature of around 560°C) up to 465°C (inlet of the second reaction zone). The pressure of the reaction gas mixture 1 in this place is 2,56 bar.

When passing through the second tubular reactor, the temperature of the reaction gas mixture 1 is held to a maximum of 560°C, which is displaced during the continuous operation of the test set due to the smooth deactivate the catalyst in the flow direction (velocity offset is roughly 0.1 mm/h). Leaving the second reactor for the dehydrogenation reaction gas mixture 1 has the following composition:

vol.%
methane0,078
Ethan0,144
Eten0,063
propane26,6
propene 4,94
H2to 6.43
O20
N258,58
CO0,384
CO2to 3.58
ISO-butane0,22
n-butane0,094
TRANS-butene0,063
ISO-butene0,001
CIS-butene0,01
1-butene0
butadiene0,004

Its temperature leaves OK. 493°C and its pressure is OK. 2,52 bar.

Before entering the next heater to the reaction gas mixture 1 serves 98 nl/h of compressed air (23°C, 4,2 bar).

Then the reaction gas mixture 1 is heated using an electric heating capabilities (the wall temperature of around 540°C) and pre-heating the next (third) reaction tubes (wall temperature of around 540°C) at 521°C (the third reaction zone). The pressure of reaction is ionic gas mixture 1 in this place is 2,52 bar.

When passing through the third tubular reactor the temperature of the reaction gas mixture 1 is held to a maximum of 570°C, which is displaced during the continuous operation of the test set due to the smooth deactivate the catalyst in the flow direction (velocity offset is roughly 0.1 mm/h). Leaving the third reactor for the dehydrogenation reaction gas mixture 1 has the following composition:

vol.%
methane0,1046
Ethan0,144
Eten0,0743
propane25,22
propene5,51
H24,69
O20
N260,10
CO0,237
CO23,54
ISO-butane0,201
n-butane 0,085
TRANS-butene0,070
ISO-butene0,0013
CIS-butene0,011
1-butene0,0004
butadiene0,0056

Her temperature is 480,4°C and its pressure 2,48 bar.

This is obtained at the stage of dehydrogenation (reaction stage 1) in terms of single pass of the reaction gas source mix 1 total conversion of propane dehydrogenation of 19.91 mol.%.

In progressive deactivation of the catalyst filling dehydrogenation method is interrupted and recovered as described in document DE-A 10028582. This is always when the temperature of the hot spot in all three tubular reactors is about 580°C.

Unexpectedly deactivated catalyst filling dehydrogenation progresses slowly with increased operating pressure.

C) Executing the release side components

By directly cooling the sprayed cooling water (T=20°C) leaving the third reactor for the dehydrogenation product gas mixture 1 is cooled in a direct cooler to 40°C (remaining at this gaseous mixture is taken to counter ologna the direction of the flow grocery output mixture from the installation). About 75 wt.% contained in the product gas mixture 1 of water vapor (water vapor fed to the reaction gas source mixture 1, and is formed at the stage of dehydrogenation by burning hydrogen and hydrocarbon oxygen; heat of combustion supports mainly the reaction temperature in the reaction gas mixture) is condensed by direct cooling. The resulting condensate is removed from water cooling and served on disposal. Otherwise used for direct cooling water is supplied in a loop (heated), through direct heat exchange again cooled and for direct cooling sprayed again.

Instead of the described direct cooling water product gas mixture 1 with stage dehydrogenation can be cool due to the fact that the product gas mixture 1 in the direct heat exchanger (for example, shell-and-tube heat exchanger in a co-current or counter-current) heat supplied to the stage dehydrogenation reaction gas source a mixture of 1 (for example, to a temperature in the range from 350 to 450°C). The product gas mixture of the dehydrogenation stage 1 is cooled in a corresponding degree with high output temperature stage dehydrogenation (for example, from 450 to 550°C) up to approx. 200 to 300°C.

Subsequent cooling of the product gas mixture 1 is Tadei dehydrogenation can be carried out by that it is used in an indirect heat exchanger in order to heat the reaction gas source mix 2 for partial oxidation obtained at the stage of dehydrogenation of propene, and/or used in order to compensate for the cooling absorbing waste gases at preferably two-stage expansion.

After that, the product gas mixture 1 is at a temperature of approx. 180°C. In conclusion, it can be cooled by a water cooler or surface cooler to a temperature in the range from 30°to 60°C.

Integrated in coolers or connected to them drip sump collect condensed by cooling water and serve it on the clearance.

The cooled and freed from water vapor at a pressure of 2 bar product gas mixture 1 stage dehydrogenation then condense to a pressure of from 10 to 13 bar.

Seal conduct an expedient manner in two stages, in order to prevent too high temperature seals (this goal are already done up to this cooling, the allocation of water vapor additionally balances the applied power seal). In the first stage to condense pressure Stufe from 4 to 4.5 bar. The output temperature of the gas mixture is when leaving the seal approx. 115°C.

To connect the hinnon indirect heat exchanger (air cooler or surface water chiller) the gas mixture is cooled to a temperature of from 40 to 60°C, moreover, there is a further condensation of water vapor. Drip sumps collect the condensate and remove it through the gateway.

In the second stage seal from pressure of approx. 4 bars compacted to a final pressure of 10 bar (there can be sealed, if necessary, to a pressure of 13 bar and more). Output temperature when leaving the seal is approx. 126°C.

In the next two downstream indirect heat exchangers (first air cooler (in the normal case, the shell-and-tube heat exchanger to be cooled gas flows through the inside of the pipe) and then surface water chiller) densified gas mixture is cooled first, from 40 to 60°C and then to 30°C. While the condensed water is then asserted drip sump and discharged. When leaving the second seal gas mixture contains only approx. 0.2 wt.% water. Low water content reduces the formation of water and prevents due dwuhfaznosti fluid production problems during the subsequent absorption, and high pressure reduces required for absorption amount of absorption of the agent.

While for compacting Kropotkinsky turbocharger (for example, type 12 MN 4B, firm Mannesmann DEMAG, DE), here applied membrane air compressor MV 3459 II firm Sera. In principle, the comp is essary can operate as a motor, and steam or gas turbines. Often drive through a steam turbine is the most economical. Compacted and cooled gas mixture is fed directly over the bottom part in the column for absorption (approx. 4650 g/h). It has the following composition:

vol.%
nitrogen61,22
oxygen0,25
propane24,23
propene5,07
methane0,02
Ethan0,11
Eten0,03
n-butane0,06
ISO-butane0,09
n-butene0,04
ISO-butene0,10
1,3-butadiene0,00
hydrogento 5.57
carbon monoxide 0,05
carbon dioxide3,15

The absorption column is made of stainless steel 1.4571. The internal diameter of the column is 80 mm, wall thickness 4 mm, length columns 1,70 m

About 70% of the volume of the absorption column filled with supplementary elements of the company Montz (Montz BSH-750, specific surface area of 750 m2/m3as effective for the separation nozzles. Packed elements follow each other immediately and start at the height of 1/5 of the length of the column. Absorption column outside is not cooled and is not heated. In the upper part of the column served with a temperature of 30°C technical tetradecane company Haltermann, DE, type PKWF 4/7 af as absorption agent (gas chromatography analysis by FID detector shows at the beginning of the following composition:

n-tridecane of 7.6%,

n-tetradecane of 47.3%

n-pentadecane 7,0%,

n-hexadecan of 3.2%,

n-heptadecane 14,1%

the residual sum of 20.7%.

This composition has changed during (after approx. 3000 h-1) continuous operation up to the following values:

n-tridecane of 2.6%,

n-tetradecane of 39.5%,

n-pentadecane of 9.4%,

n-hexadecan of 4.8%,

n-heptadecane 23.4%, and

the residual sum of 20.3%.

Gravity irrigation is 15 m3absorption agent on m2free surface transverse of the CoE is to be placed and hours (=28 kg/h tetradecane).

Supplied from the absorption column as a release side components for combustion air flow exhaust gas still contains about 950.%-million including propane and 250 rpm.-million hours of propene. In krupnoseriynom scale this exhaust gas is supplied to the combustion through the expander (for example, an expansion turbine)to regenerate the most part applied in the two-stage seal power and recycling on the two-stage seal. Appropriate, the extension also perform the two-step, to avoid unwanted condensation. Obtained by extending the mechanical energy can be used as an additional or primary drive and/or to obtain the current.

Before advanced othonoi gas absorption is burning, it may be appropriate Department of the contained hydrogen. This may be due to the fact that the exhaust gas is fed to the membrane, which is permeable only to molecular hydrogen. Separated thus hydrogen can be recycled for heterogeneously catalyzed partial dehydrogenation or for other applications.

In principle, the separation of hydrogen may also be partial condensation, adsorption (adsorption with variable pressure) and/or by distillation (preferably under pressure). As a rule, it is advisable the environment, which administers the gas absorption to guide you through the acidic water, in order to concentrate.

Absorbed contains the following components (wt.% in terms of weight absorbate):

wt.%
nitrogen0,147
propane4,58
propene0,915
Ethan0,07
n-butane0,015
ISO-butane0,023
n-butene0,009
ISO-butene0,024
carbon dioxide0,086
Eten0,000
tetradecaneapprox. the remainder to 100 wt.%

Before absorbed fed to the upper part of the subsequent desorption columns, it is heated in indirect heat exchanger to 60°C. Then absorbed (this may be done, for example, in the inversion pump or by valve), which expands to a pressure of 2.7 bar (released in the case of inverse the frame pump mechanical energy applied appropriate way to reverse the seals released in the desorption column absorption agent) and any resulting two-phase mixture is fed to the upper part desorption columns.

In the desorption column (inner diameter 80 mm, length 1.70 m, wall thickness 4 mm) are served from the bottom in countercurrent to the flue from the top of the desorption column to absorbate pressure of 3 bar air (1269 nl/h). Lodged in the upper part of the column the number of absorbate is 33.7 l/h Output at the bottom of the desorption column, mainly released from the desorbed components of the absorption agent is cooled by indirect heat exchange, compacted to the desired Stripping in the Stripping column pressure, is cooled by another indirect heat exchange (suitable way surface water) to 16°C and then recycle to the upper part of the column. As effective for separation nozzles desorption columns use structured sheet metal attachments firm Montz (Montz BSH-750, specific surface area of 750 m2/m3). To keep desorption agent supplied from the desorption column gas stream is washed with water. This means that it is served through the nozzle element of the firm Montz (Montz BSH-750, specific surface area of 750 m2/m3), serves on water (70 l/h) with a temperature of 18°C in the counter. Under the showerhead is catching plate (mantel plate), which you can display the aqueous phase. In phase sump is divided into the aqueous phase and the organic Fazal number the combined organic phases are returned to the upper part of the absorption column by the flow of the absorbed agent. The aqueous phase is cooled and complement the fresh water to compensate for evaporation) and again served on the Packed item, and then washed.

From the site of washing the washed gas stream through a manual drip sump (pooled liquid phase return on leaching) output with the following composition (if the reaction stage 1 conversion of the dehydrogenation selected above, the following content of propene can be from 8 to 12 vol.%; for example, the washed gas stream can have 15% vol. propane, 10% vol. of propene and 14.5% vol. O2):

vol.%
nitrogen46,69
nitrogen11,84
propane32,53
propenefor 6.81
Ethan0,07
n-butane0,08
ISO-butane0,12
n-butene0,05
ISO-butene0,13
hydrogen 0,07
carbon monoxide0,00
carbon dioxide0,61
water1,00
Eten0,00

The temperature of the gas mixture increases in indirect heat exchange to 250°C and the gas mixture with the above composition in an amount 2128 nl/l·h and the inlet pressure of 2.1 bar as a new reaction gas source mix 2 serves in the following partial oxidation device.

C) Executing the second and third reaction stage (partial oxidation)

1. The first reactor with a fixed bed for the partial oxidation of propene (propylene) to acrolein:

applied heat transfer agent:salt melt consisting of
53 wt.% potassium nitrate,
40 wt.% sodium nitrite and
7 wt.% sodium nitrate
the dimensions of the contact pipe:4200 mm overall length
26 mm inner diameter,
30 mm outer diameter,
2 m wall thickness

The reactor consists of a cylinder with a double wall of stainless steel (cylindrical guide tube surrounded by a cylindrical external tank). Wall thickness is anywhere from 2 to 5 mm.

The inner diameter of the outer cylinder is 168 mm, an Inner diameter of the guide pipe is approx. 60 mm

The top and bottom cylinder with double walls is closed by a cover, respectively, the bottom.

Contact the pipe is located in a cylindrical tank so that its upper and lower end withdrawn (with seal) turn the cover, respectively, the bottom of every 250 mm

Heat transfer agent is enclosed in a cylindrical container. To ensure that all are in cylindrical vessels, the length of the contact tube (3700 mm) uniform thermal framework conditions on the outer wall of the contact tube, the heat transfer agent is stirred by entering of bubbles of nitrogen in a cylindrical container.

With rising nitrogen heat transfer agent in a cylindrical guide tube is fed from the bottom up, then in the intermediate space between the cylindrical guide tube and a cylindrical external tank again flow down (circulation of the same quality can be achieved by pumping (e.g., propeller, naaso is)). By using a host on the external casing of the electric heating temperature of the heat transfer agent can be adjusted to the desired level. In the rest of the available cooling air.

Download reactor:

if you look along the reactor, salt melt and reaction gas mixture 2 is directed in counterflow. The reaction gas mixture 2 is included in the reactor from the top. She is fed into the reaction tube with a temperature of 250°C. molten Salt is included at the bottom of the cylindrical guide tube with a temperature Tein=335°C and out of the cylindrical guide tube with a temperature Taus. The difference between the Teinand Tausis roughly 2°C. Tmittel=(Tein+Taus)/2.

Download contact tubes (top to bottom):

segment a: 50 cm long pre-filling of steatite rings (steatite C 220 CeramTec) of geometry 7 mm × 7 mm × 4 mm (external diameter × length × internal diameter).

Length: 100 cm

Download contact tubes homogeneous mixture of 20 wt.% (alternative 30 wt.%) steatite rings (steatite C 220 CeramTec) of geometry 5 mm × 3 mm × 2 mm (external diameter × length × internal diameter) and 80 wt.% (alternative 70 wt.%) the solid catalyst of the segment C.

Cut To: 170 cm in length

Download catalyst annular (5 mm × 3 mm × 2 mm = external diameter × length × internal diameter is Tr) a solid catalyst according to example 1 of document DE-a 10046957.

Segment D: 50 cm

Subsequent backfilling of steatite rings (steatite C 220 CeramTec) of geometry 7 mm × 7 mm × 4 mm (external diameter × length × internal diameter).

2. Intermediate cooling and intermediate oxygen supply

Leaving the first reactor with a fixed bed product gas mixture 2 to the intermediate cooling (indirectly through air) is directed through the connecting pipe (length 400 mm, internal diameter 26 mm, wall thickness 2 mm, material stainless steel, which is centered along the length of 200 mm, is loaded with an inert filling of steatite rings (steatite CeramTec) of diameter 5 to 6 mm and prihlasovani directly to the contact tube of the first reactor with a fixed bed.

The gas mixture enters the connecting pipe with temperatures higher than 310°C and exits with a temperature of approx. 140°C. Then to the gas mixture as the source of oxygen admixed 269 nl/h of compacted air.

Rezultirase when mixed in a static mixer boot gas mixture served with a temperature of 220°C. to the reactor with a fixed bed stage partial oxidation of acrolein to acrylic acid.

3. The second reactor with a fixed bed for partial oxidation of acrolein to acrylic acid

Used reactor with a porous layer that Odie is akov design with the first stage reactor. Salt melt and reaction gas mixture serves, when viewed along the reactor in co-current. Molten salt is included at the bottom of the reaction gas mixture, too. Download the contact tube (top to bottom) as follows:

segment a: 20 cm

Pre-filling of steatite rings (steatite C 220 CeramTec) of geometry 7 mm × 7 mm × 4 mm (external diameter × length × internal diameter).

Length: 100 cm

Download the catalyst is a homogeneous mixture of 20 wt.% (alternative 30 wt.%) steatite rings (steatite C 220 CeramTec) of geometry 7 mm × 3 mm × 4 mm (external diameter × length × internal diameter) and 80 wt.% (alternative 70 wt.%) shell catalyst of the segment C.

Cut To: 200 cm in length

Download annular (7 mm × 3 mm × 4 mm = external diameter × length × internal diameter) shell catalyst according to exemplary embodiment 5 of the document DE-A 10046928 (this place could be applied in similar and accordingly made shell catalysts, the active mass of which has a stoichiometry Mo12V2,8W1,2Cu2,4Oxor Mo12V3,5W1,3Cu2,4Ox).

Segment D: 50 cm

Subsequent backfilling of steatite rings (steatite C 220 CeramTec) of geometry 7 mm × 7 mm × 4 mm (external diameter × length × internal diameter).

The second reactor is of Rugen approx. 3607 g/h boot gas mixture (reaction gas source mixture 3). Tmitteldefined as for a reactor of the second reaction stage, and 284°C.

The conversion of propene in the first reaction stage was 98.0 mol.%, and conversion acrolein in the second reaction stage is approx. and 99.8 mol.%.

The composition leaving the second reaction stage with a temperature of 281°C and a pressure of 1.8 bar product gas mixture 3 is as follows:

vol.%
nitrogen51,54
oxygen2,3
propane29,20
propene0,110
methane0
Ethan0,077
n-butane0,101
ISO-butane0,236
n-butene0
ISO-butene0,001
1,3-butadiene0,009
hydrogen0,05
carbon monoxide0,596
carbon dioxide1,72
water8,21
acrolein0,009
acrylic acid5,28
acetic acid0,240
propionic acid0,002
formic acid0,019
formaldehyde0,198
benzaldehyde0,005
anhydride0,047
maleic acid
methacrolein0,020
methacrylic acid0,011
Etento 0.032

Applied on both reaction stages 2, 3 catalysts can be replaced by used in the examples document the DE-A 10351269 catalysts. The catalyst of the second reaction stage may be replaced by a catalyst of examples and comparative example document DE-A 10344149. The catalyst in the third reaction stage may be replaced by the catalysts of examples of document DE-A 10360057 and document DE-A 10360058. Next, partial oxidation can be carried out as a way to high load, as it is described in the documents DE-A 10313210, DE-A 10313213, DE-A 10313212, DE-A 10313211, DE-A 10313208, DE-A 10313209 and DE-A 10313214 and given in these documents of the prior art.

C) Performing the separation zone And the selection of the target product of acrylic acid from product gas mixture 3 partial oxidation)

In the direct cooler hot stream of product gas mixture (product gas mixture 3) in parallel (after merging with below-loaded flow strip gas) by means of a flow through the nozzle coolant liquid (containing 57,4% wt. diphenyl ether, 20,7% wt. of diphenyl, 20 wt.% o-dimethylphthalate and as residual amounts to 100 wt.% fenotiazina (up to 1 wt.%), as well as high-boiling substances (for example, oligomers of acrylic acid)) temperature from 140 to 150°C, which are used as absorption agents, cooled to approx. 180°C. In the lower part of the direct cooler is going not evaporated cooling liquid is selected and through the heat exchanger, in which she again dovalidate initial temperature, is injected again in the upper part of the cooler. The stream of product gas mixture 3 (combined with loaded strip-gas) and rsprasanna nozzles in a jet of cooling fluid are served in parallel to the direct cooler. The cooled product gas mixture 3 then flows into the next absorption column. In the cooling cycle enriched high-boiling by-products that must be removed through the gateway. From the cooling cycle so once a day discontinuously descends partial amount of coolant in the tank that is using a rotary evaporator (8 mbar, 180°C) discontinuously processes. The resulting purified condensate absorption agent is fed to a buffer tank to drain from the bottom of the wash column, and once a week occurred during processing in a rotary evaporator loss absorption agent in 2.9 g/h is replaced by a fresh mixture of diphenyl ether (of 21.2 wt.%), of diphenyl (58.8 wt.%) and o-dimethylphthalate (20 wt.%).

The cooled product gas mixture 3 is directed over the bottom part and under the bottom of the first nozzle in the absorption column. Absorption column (without the bottom) has a length 5420 mm, and has an internal diameter of 50 mm and contains in total length 3.3 m nozzles firm Kuehni (CH) Rhombopak 9M.

The absorption column of the imp is replaced glass and considerations tempering is segmented double casing of glass. Directly on top of the second nozzle, looking from above, there is a valve for relieving pressure (adjustable choke), with which you can simulate the loss of pressure in the absorption column from 100 to 300 mbar. The absorption column is operated at a pressure in the head part of 1.30 bar and in the lower part of 1.40 bar. The temperature in the lower part is approx. 113°C. the Double casing of glass is divided into five successive segments in which the absorption column given below the temperature profile. This segmentation should also internal structure of the absorption column.

The segments are from the bottom up following the temperature (temperature control is using pumped water, respectively, in the first segment of teplonasosy oil the right temperature) and calculated as follows:

segment 1: 1020 mm in length (directed upwards, starting in place of the supply of the product gas mixture 3), 113°C, and 0.4 m robopac between directly over the bottom part of the absorption column place the supply of the product gas mixture 3 and the place of supply is continuously withdrawn and recycled to the column (approx. 113°C, in the amount of about 200 l/h) liquid bottom and 0.6 m robopac over this place of filing. The distance between the two Ambapali is 2 see

segment 2: 120 mm length, 75°C, at the bottom there is a pressure relief valve and float valve pressure relief to the place of supply of the stream of low-boiling condensate of the following sequential distillation is robopac 0.5 m

segment 3: 950 mm length, 60°C, 0,6 m robopac that begin directly over the inlet of the condensate of the low-boiling substances of the second segment.

segment 4: 950 mm long, 50-55°C, 0,6 m robopac that end directly under the place of supply of the main stream of the absorption agent.

segment 5: 1250 mm length, 20°C, 0,6 m robopac between which is located directly over the inlet of the absorption agent in the segment 4 to enter the acidic water-absorbing plates and place of filing recycled acidic water in the upper part of the absorption column.

From being in the fifth segment of the arresting plates divert rich water condensate (approx. 70,2 l/h). It is cooled in the heat exchanger indirectly to 20°C and mostly over the top rombo-nozzle then returned to the absorption column (70 l/h). Outstanding share taken acidic water (reaction water) is brought out through the gateway and serves phase extraction of acidic water. At this stage, derived through the gateway acidic water is combined in held at an ambient temperature of tubular containers, of glass (1 liter volume, 80 mm diameter) when d is in relation to the environment with partial thread a little loaded (acrylic acid and side components) absorption agent, and mixed. Rezultiruyushchuyu mixture constant release held at an ambient temperature of glass containers (7.5 l volume, 150 mm diameter) through the free pass. There deflated liquid mixture separates into two liquid phases, the sour side components (e.g., acetic acid) preferably pass into a lighter phase and acrylic acid in the heavy organic phase. The organic phase is combined with the supplied force diaphragm pump for the most part a little loaded absorption agent and the gas flow (approx. 3.0 l/h, 40°C), as already described, leading directly to the capture plate as the main stream of the absorption agent absorption columns.

Leaving the absorber column in the upper part of the residual gas (T=20°C, P=1,30 bar) has the following composition:

vol.%
nitrogen59,9
oxygento 2.67
propane33,93
propene0,128
methane0
Ethan0,09
n-butaneamount of 0.118
ISO-butane0,274
n-butene0

ISO-butene0,001
butadiene0,010
hydrogen0,058
carbon monoxide0,693
carbon dioxide1,97
acrolein0,009
Eten0,037
all the above contents were calculated without water
water1.78 (in terms of all)

Through direct heat exchange heats up (main) residual gas to 40°C, by a diaphragm compressor (krupnoseriynom scale driven by an electric motor of the turbocharger, for example, type MW, the Irma Mannesmann DEMAG, DE) condense to 2.70 bar and recycle approx. 78% as the principal3-circulating gas to download the first dehydrogenation reactor at the reaction stage 1.

About 22% vol. compacted (main) residual gas during expansion to 1.6 bar and the scrubber is made of stainless steel (material 1.4571, inner diameter 30 mm, content: 2 m robopac 9M) at approx. 1.6 bar and about 51°C, washed neuobicajenim the General flow of the absorption agent in the counter-current (lowest image loaded absorption agent is fed to the column at the top and the gas is fed at the bottom).

In another pressure column made of stainless steel (material 1.4571, inner diameter 30 mm, content: 3 m Rhombopak 9M, double shell-tempered butter = strip-column) this washed gas stream using at 1.5 bar and approx. from 119 to 125°C to-Laden flow absorption agent, which constant is given from the bottom of the absorption column (approx. 3,5 l/h, approx. 113°C)to remove low-boiling components (e.g., as described in DE-a 10336386). Resultwise when loaded low-boiling components (more volatile than acrylic acid) gas flow (loaded strip-gas) is heated in tempered at 170°C and line with a double casing (diameter 15 mm, the outer casing of stainless steel) and unite at the entrance to ohlazhdyonkoj with a hot stream of product gas mixture 3.

At the lower end of the scrubber stainless steel is a bit loaded stream absorption agent down in the above-mentioned buffer capacity (glass, 5 l volume) (in this tank serves also formed in the rotary evaporator condensate absorption agent).

From the buffer tank using a membrane pump more partial flow of 2.5 l/h is a bit loaded absorption agent is directed to the absorption column and there, as already described, as a component of the main stream of the absorption agent under load detecting plate for release of acidic water in the segment 4. The smaller partial stream in 460 ml/h is a bit loaded absorption agent through another membrane pump served in a glass mixing phase extraction of acidic water.

From the series the bottom of strip-columns (approx. 100 l/h, the membrane pump pressure air) divert approx. 3.5 kg of liquid to the lower part through a fabric filter and a regulating valve for pure distillation serves to node vacuum distillation.

Site vacuum distillation unit consists of a vacuum insulated glass columns (clear columns) with an inner diameter of 50 mm and a length of 4000 mm cycle bottom of the column forced expansion (approx. 250 l/h, centrifugal pump with peripheral impeller) keep the temperature the lower is her part of the column at 191°C (p 4 bar). The absolute pressure in the lower part of the column is approx. 230 mbar, the pressure in the upper part of the column is 100 mbar. For inhibition of polymerization on top of the lower part of the column serves 52 nl/h of air.

Between the bottom of the vacuum distillation column and the flow-Laden product stream from the cycle the lower part of strip-columns in the column vacuum distillation first set 6 of bubble cap trays (distance between plates: 5 cm) and the top (over supply) 15 bubble cap trays (the distance between the plates 5 cm), on top of which there is a possibility of sampling using miniature diaphragm dosing pump.

On top of that selection points are 10 sieve plates (each plate 6 equally spaced holes with a diameter of 6.5 mm) (distance between plates: 5 cm), which extend up to the catching plates, which continuously taken out through the gateway approx. 364 g/h of purified acrylic acid as the target product and after cooling loads in the collection.

The composition of the side components of the target product is as follows:

acrylic acid (purity containing no inhibitor)99,54 wt.%
all these side lobe components is given here as the weight of the quantities in terms of the obtained acrylic acid
acetic acid0,186%
propionic acid269 million hours
the anhydride of maleic acid406 million hours
formaldehyde344 million hours
benzaldehyde186 million hours
methacrylic acid1597 million hours
water342 million hours

On the top from under the tap of the target product stochnyh plates further recycle number (732 ml/h) the decision of the arresting plate of acrylic acid, while maintaining its temperature at approx. 75°C distillation column.

Over the yield of the target product is 10 / tube sheet plates (each plate 6 holes with a diameter of 5.5 mm, the distance between the plates: 5 cm), which allows to enrich the remaining low-boiling components to the bottom of the column. On top of these / tube sheet plates is another absorbing plate to catch the condensate of the low-boiling components, which is due to indirect cooling cond is ncacii in the upper part of the column (26°C, 100 mbar absolute pressure), the temperature detecting plate is 73°C. low-boiling condensate contains:

acrylic acid98,42 wt.%
acetic acid1,02 wt.%
water0,427 wt.%
metafolin0.012 wt.%
metallova acid0,021 wt.%
devil0,009 wt.%
propionic acid0,024 wt.%
furan-2-aldehyde0,010 wt.%
allylacetate0,009 wt.%
acrolein0.002 wt.%

From the catching plate flow condensate of the low-boiling components in the main thread in 570 ml/h again under load detecting plate of the low-boiling components as the phlegm in the distillation column. While it remains condensate flow low-boiling components in 190 ml/h, cooled to 40°C and served on top of the second segment absorbtsionnoi column of acrylic acid. For inhibiting the wetting of the walls in the upper zone of the upper part of the column serves stabilized by 0.5 wt.% fenotiazina stream of the desired product in 51 ml/h with a temperature of 25°C over truevue nozzle with 4 holes.

Allocated in the upper part of the clean column by a diaphragm vacuum pump of the gas stream consists of inert gases and low-boiling components. Cooled to 8°C low-temperature trap could be separated from him 4,6 g/h condensation of residual low-boiling components. This liquid condensate residual components contains:

acrylic acid89,65 wt.%
acetic acid2.45 wt.%
water7,24 wt.%
methacrolein0,197 wt.%
methacrylic acid0,029 wt.%
devil0,059 wt.%
propionic acidat 0.020 wt.%
furan-3-aldehyde0,021 wt.%
allylacetate to 0.007 wt.%
acrolein0,037 wt.%

The remaining stream of inert gas condensing the residual component has the following composition:

Its recycle over valve pressure relief and under the above Rhomopak-nozzles on the second segment of the absorption column.

In the lower part of the net column divert exempt from acrylic acid absorption agent and as little loaded flow absorption agent fed to the scrubber, and the increasing pressure of the circulation pump lower part of the column used for output from a vacuum. Little loaded absorption agent:

vol.%
nitrogenthe remainder to 100%
oxygen1,20
propane18,8
propene0,08
methane0,004
Ethan0,052
n-butane0,069
ISO-butane0,146
n-butene0
ISO-butene0,0
butadiene0,010
carbon monoxide0,372
carbon dioxide1,88
Eten0,022
wt.%
acetic acid0,012
furan-2-aldehyde0,0000
propionic acid0,0000
benzaldehyde0,097
acrylic acid0,056
methacrylic acid0,017
devil77,5
DMP20,0
benzoic acid0,642
di-acrylic acid 0,910
water0,0283

To reduce losses to the original material, as well as to achieve high conversion of all loaded the original product or the target product streams of gases analysis is collected in a glass bottle (0.5 l) and using a small diaphragm pump down to the first stage seal release side components and before sealant combine with the cooled product gas mixture 1 stage dehydrogenation and then condense. In terms of converted propane, get out of acrylic acid 78,9 mol.%.

In terms of contained in the product gas mixture 3 propane and propylene, propane and propylene get the pistons back in > 98 mol.% in the first reaction stage. In the separation of acrylic acid from product gas mixture 3, wherein product gas mixture fraktsionirovannoe condense, after what happened, if necessary, direct and/or indirect cooling in containing effective for separating nozzle column, pick up a side drainage of crude acrylic acid and/or absorb water solution, as described in document WO 2004/035514 and DE-A 10243625, the above-mentioned degree of return are typically > to 99.9 mol.% and more. This is based on the fact that the water environment is Roman and propylene mostly not absorb and exhaust in the upper part of the column of circulating oxidative gas (residual gas) contains unreacted propane and propylene mainly quantitatively. Further purification of selected crude acrylic acid is suitable manner by means of suspension crystallization and subsequent separation in the scrubber suspension kristalliset described in the present description.

Obtained as the target product of the crude acrylic acid is subjected to further purification as described in document EP-A 616998 (when the document EP-A 912486) or in DE-A 19606877 or as in document EP-A 648732 crystal or distillation to pure acrylic acid, which can then be polymerized in a known manner. As the resulting crude acrylic acid, and obtained pure acrylic acid suitable for the production of esters of acrylic acid, for example, to obtain akilakilov.

Essential according to the invention is that the method according to the invention is also suitable when the second reaction stage is carried out in a tubular shell-and-tube reactor and loading contact tubes in the second stage from the top down in the direction of flow of the reaction gas mixture 2 is as follows:

segment a:50 cm long pre-filling of steatite rings (steatite C220 CeramTec) of geometry 7 mm × 7 mm × 4 mm (external diameter is × length × internal diameter)
segment:100 cm long catalyst loading homogeneous mixture of 30 wt.% steatite rings (steatite C220 CeramTec) of geometry 5 mm × 3 mm × 2 m (external diameter × length × internal diameter) and 70 wt.% the solid catalyst of the segment
cut To:170 cm long catalyst loading circle solid catalyst (5 mm × 3 mm × 2 mm = external diameter × length × internal diameter) according to example 1 of document DE-A 10046957
cut D:50 cm long subsequent backfilling of steatite rings (steatite C220 CeramTec) of geometry 7 mm × 7 mm × 4 mm (external diameter × length × internal diameter)

According to the invention it is essential that the method according to the invention is also suitable when the second reaction stage is carried out in a tubular (tube) reactor and in the reactor salt melt and reaction gas mixture 2 is directed not at the counter.

The above really especially when loading contact tubes is not as described above.

The method according to the invention is also suitable when between the second and third reaction stages is intermediate p the food with oxygen.

The method according to the invention is also suitable when the third stage is carried out in a tubular (tube) reactor and contact tubes are loaded reaction gas mixture 3 as follows:

segment a:20 cm long pre-filling of steatite rings (steatite C220 CeramTec) of geometry 7 mm × 7 mm × 4 mm (external diameter × length × internal diameter)
segment:100 cm long catalyst loading homogeneous mixture of 30 wt.% steatite rings (steatite C220 CeramTec) of geometry 5 mm × 3 mm × 2 m (external diameter × length × internal diameter) and 70 wt.% shell catalyst of the segment
cut To:200 cm long catalyst loading of the annular shell catalyst (5 mm × 3 mm × 2 mm = external diameter × length × internal diameter) according to example 5 of document DE-A 10046928
cut D:50 cm long subsequent backfilling of steatite rings (steatite C220 CeramTec) of geometry 7 mm × 7 mm × 4 mm (external diameter × length × internal diameter)

According to the invention is further significant is the fact that the JV is the FDS according to the invention is also suitable and then when the third reaction stage is carried out in a tubular (tube) reactor and in the reactor is sent to the salt melt and reaction gas mixture 3 is not parallel.

According to the invention is further significant is the fact that the method according to the invention is also suitable when the second and third reaction stage is carried out in a tubular (tube) reactor and loading contact tubes from top to bottom in the direction of flow of the reaction gas mixture on both stages is not as described above.

According to the invention is further significant is the fact that the method according to the invention is also suitable when the second and third reaction stage is carried out in a shell-and-tube reactors, in which the fluid (molten salt) flows in the form of a meander.

According to the invention the method according to the invention is also suitable when the second reaction stage does not apply no solid catalyst according to example 1 of document DE-A 10046957 or the catalyst according to the examples of the document DE-a 10351269, nor according to the examples or comparative examples document DE-a 10344149.

According to the invention the method according to the invention is also suitable when the third reaction stage does not apply shell catalyst according to any exemplary embodiment 5 of the document DE-A 10046928 or shell kata is isator with active mass Mo 12V2,8W1,2Cu2,4OxMo12V3,5W1,3Cu2,4Oxor the catalyst according to example documents DE-A 10351269, DE-A 10360057, and also DE-A 10360058.

In particular, the method according to the invention is also suitable when the separation of acrylic acid from product gas mixture 3 is not happening with absorption agent, which contains 57,4% wt. diphenyl ether, 20,7% wt. of diphenyl and 20 wt.% o-dimethylphthalate.

The method according to the invention is also suitable when it is a combination of the above negative traits (in particular, does not have the combination of all the negative signs).

1. The method of reducing the temperature of the hot points of a fixed catalyst layer on the first stage partial oxidation in the process of obtaining acrylic acid by two-stage heterogeneously catalyzed partial oxidation in the gas phase propylene, in which
A. in the first reaction stage propane in the presence of and/or with the exclusion of oxygen is subjected to a heterogeneously catalyzed dehydration, and get containing propane and propylene, and other than propane and propylene components, the product gas mixture 1, and
b. from the educated to the first reaction stage product gas mixture 1, if necessary, make a partial number of soderjaschihsya it other than propane and propylene components, such as hydrogen and carbon monoxide, in other connections, other than propane and propylene, and formed in the first reaction stage product gas mixture 1, if necessary, separate the partial quantity contained therein other than propane and propylene components, such as hydrogen, carbon monoxide and water vapor from the product gas mixture 1 receive product gas mixture 1'containing propane and propylene, and other than oxygen, propane and propylene compounds, and
C. the product gas mixture 1 or product gas mixture 1' as a component of the source of the reaction gas mixture 2 containing molecular oxygen, molecular nitrogen, propane and propylene in such a quantity that the molar ratio of O2:C3H6≥1 and the molar ratio of N2:O2is 2-6, loaded catalyst fixed bed 2, the catalysts whose active mass have, at least, one containing the elements Mo, Fe and Bi oxide multimetallic, the second reaction stage is subjected to a heterogeneously catalyzed partial oxidation in the gas phase contained in the product gas mixture 1 or product gas mixture 1' propylene to acrolein, and get a mixture of 2 product gas (hereinafter: the product gas mixture 2), and
. the temperature leaving the second reaction stage product gas mixture 2, if necessary, reduce direct and/or indirect cooling, and to a product gas mixture 2, if necessary, add molecular oxygen and/or inert gas, and
that is, after that as a starting reaction gas mixture 3, which contains molecular oxygen, molecular nitrogen, propane, acrolein, and the molar ratio is About2:C3H4O≥0,5, loaded catalyst fixed bed 3, the catalysts whose active mass have, at least, one containing the elements Mo and V oxide multimetallic, the third reaction stage is subjected to a heterogeneously catalyzed partial oxidation in the gas phase contained in the source of the reaction gas mixture 3 acrolein in acrylic acid, and receive a mixture of 3 product gas (hereinafter: the product gas mixture 3), and
f. from the product gas mixture 3 in the separation zone And separating acrylic acid, which if necessary, cleaned, and at least contained in the product gas mixture 3 unreacted propane and propylene return each of at least 80 mol.%, in terms of contained in the product gas mixture 3 the amount of each, for at least the first of the three reaction hundred is s, characterized in that
i. the second reaction stage is carried out until the degree of conversion UPpropylene, which is ≤99 mol.%, in terms of a one-time pass through it, and
ii. the third reaction stage is carried out until the degree of conversion UAacrolein equal to ≥96 mol.%, in terms of a one-time pass through it, the method includes at least one separate selection for other than propane and propene components, which contains propane and propene in the number of ≤5%vol.

2. The method according to claim 1, characterized in that the UPis ≤to 98.5 mol.%.

3. The method according to claim 1, characterized in that the UPis ≤a 97.5 mol.%.

4. The method according to claim 1, characterized in that the UPis ≤97,0 mol.%.

5. The method according to claim 1, characterized in that the UPis ≤to 96.5 mol.%.

6. The method according to claim 1, characterized in that the UPis ≤96,0 mol.%.

7. The method according to claim 1, characterized in that the UPis ≤to 95.5 mol.%.

8. The method according to claim 1, characterized in that the UPis ≤95,0 mol.%.

9. The method according to claim 1, characterized in that the UPis ≥50 mol.%.

10. The method according to claim 1, characterized in that the UAndis ≥97 mol.%.

11. The method according to claim 1, characterized in that the UAndis ≥98 mol.%.

12. The method according to claim 1, characterized in that the UAndis ≥99 mol.%.

13. The method according to claim 1, characterized in that the UAwhich of 99.5 mol.%.

14. The method according to claim 1, characterized in that the UPis from 80 to 98 mol.% and UAranges from 99 to 99.9 mol.%.

15. The method according to claim 1, characterized in that the UPranges from 90 to 98 mol.% and UAranges from 99 to 99.9 mol.%.

16. The method according to claim 1, characterized in that contained in the product gas mixture 3 unreacted propane and propylene recycle each of at least 85 mol.% on at least the first reaction stage.

17. The method according to claim 1, characterized in that contained in the product gas mixture 3 unreacted propane and propylene recycle each at least 90 mol.% on at least the first reaction stage.

18. The method according to claim 1, characterized in that contained in the product gas mixture 3 unreacted propane and propylene recycle each of at least 95 mol.% on at least the first reaction stage.

19. The method according to claim 1, characterized in that at least one of the three reaction stages bring fresh propane.

20. The method according to claim 1, characterized in that the reaction stage 2, or reaction stage 3, or both reaction stages bring fresh propane.

21. The method according to claim 1, characterized in that the reaction of the source gas mixture 2 contains ≥7% vol. propylene.

22. The method according to claim 1, characterized in that the molar ratio of V 1contained in the reaction gas source mix 2 propane contained in the reaction gas source mix 2 propylene is from 1 to 4.

23. The method according to item 22, wherein the V1is from 1 to 3.

24. The method according to claim 1, characterized in that the reaction gas source mixture 3 contains ≥5,5% vol. acrolein.

25. The method according to claim 1, characterized in that the reaction gas source mixture 3 contains ≥6% vol. acrolein.

26. The method according to claim 1, characterized in that the molar ratio of V5contained in the reaction gas original mix 3 propane contained in it acrolein is from 1 to 4.

27. The method according to p, characterized in that the V5ranges from 1.5 to 3.5.

28. The method according to p, characterized in that the V5ranges from 1.5 to 3.

29. The method according to claim 1, characterized in that the reaction gas source mixture 3 contains:
from 6 to 8% vol. acrolein,
from 3 to 9% vol. molecular oxygen,
from 10 to 20 vol.% propane,
from 50 to 20% vol. molecular nitrogen and
from 7 to 13% vol. water vapour.

30. The method according to claim 1, characterized in that the load of the fixed catalyst layer 2 propylene is ≥140 nl/l·h

31. The method according to claim 1, characterized in that the load of the fixed catalyst layer 2 acrolein is ≥120 nl/l·h

32. The method according to claim 1, characterized in that the reaction study is 1 is autothermal, heterogeneously catalyzed dehydrogenation.

33. The method according to claim 1, characterized in that the reaction between stages 2 and 3 do not perform intermediate supply of oxygen.

34. The method according to claim 1, characterized in that the reaction stage 2 and 3 is carried out in a common reactor.

35. The method according to one of claims 1 to 34, characterized in that after the implementation, if necessary, direct and/or indirect cooling of the product gas mixture 3 is subjected to fractionated condensation at lifting containing effective for separation of the nozzle column, from which side drain output of crude acrylic acid and/or absorb water and/or aqueous solution.

36. The method according to p, characterized in that the purification of the resulting crude acrylic acid is carried out suspension crystallization with formation of a suspension kristalliset acrylic acid and the remaining mother liquor.

37. The method according to p, characterized in that the suspension crystallized acrylic acid is separated with at least one scrubber from the remaining mother liquor.

38. The method according to clause 37, wherein the scrubber is a scrubber with forced transport of the crystal layer.

39. The method according to clause 37, wherein the scrubber is made as a hydraulic scrubber.

40. SPO is about one of p-39, characterized in that as the wash liquid is applied to the melt pre-separated in the scrubber crystals of acrylic acid.



 

Same patents:

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of producing acrylic acid from propylene, involving a first step where propylene is oxidised to acrolein and a second step where acrolein is oxidised to acrylic acid, as well as a step for dehydrating glycerin to acrolein in the presence of a propylene-containing gas. The said step for dehydrating glycerin is carried out before catalytic oxidation of propylene to acrolein in the presence of the supplied propylene-containing gas, or after catalytic oxidation of propylene to acrolein in the presence of a gaseous mixture coming out after oxidation of propylene to acrolein.

EFFECT: method enables partial use of renewable material, while increasing output of acrylic acid.

8 cl, 5 dwg, 6 ex

FIELD: chemistry.

SUBSTANCE: in accordance with the method A) at least two propane-containing gas supply streams are fed into the first reaction zone A, where at least one of the said streams contains fresh propane, and propane fed into this reaction zone undergoes heterogeneous catalytic dehydrogenation with a fixed bed catalyst, obtaining a propane- and propylene-containing gaseous mixture of products A, B) which is extracted from reaction zone A, in the first separation zone, A is separated from at least a portion of components contained in it, which are different from propane and propylene, and the remaining gaseous mixture of products A' which contains propane and propylene C) is used in the second reaction zone B for supplying at least one oxidation reactor, and propylene contained in the gaseous mixture of products A' in at least one oxidation reactor undergoes heterogeneous catalytic two-step gas-phase partial oxidation with molecular oxygen to acrylic acid or a mixture of acrolein and acrylic acid as an end product, as well as to an excess molecular oxygen-containing gaseous mixture of products B, D) which is extracted from the reaction zone B, in the second separation zone B, the end product contained in it is extracted through absorption or fractional condensation, and at least a portion of the remaining residual gas which contains unconverted propane, molecular oxygen, and also if necessary, unconverted propylene are recycled into the reaction zone A as at least one of two propane-containing supply streams, where the said recycling into the reaction zone A is done along the path of the heterogeneous catalysed dehydrogation of propane in that reaction zone such that, at the point for feeding the recycled gas into reaction zone A at least 5 mol % of propane has already undergone dehydrogenation, where the said propane is fed into this reaction zone with other supply streams, where molar ratio of the propylene contained in the reaction gaseous mixture to molecular hydrogen contained in the said mixture within the reaction zone A does not exceed 10.

EFFECT: design of an improved method of obtaining acrolein, acrylic acid or their mixture from propane.

41 cl, 3 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of continuous, heterogeneous, catalytic, partial gas-phase oxidation of at least one organic compound selected from a group comprising propene, acrolein, isobutene, methacrolein, isobutene and propane, in an oxidation reactor loaded with a gas mixture which, along with at least one compound to undergo partial oxidation and molecular oxygen as an oxidation agent, includes at least one diluent gas which is essentially inert in conditions of heterogeneous, catalytic, gas-phase partial oxidation, where the source of oxygen and inert gas for the loaded gas mixture is air which is compressed in a compressor beforehand from a low initial pressure value to a high final pressure value, where before entering the compressor, the air undergoes at least one mechanical separation procedure through which particles of solid substance dispersed in the air can be separated.

EFFECT: method prevents negative effect of solid particles on the air compression stage, undesirable increase in pressure loss and reduction of activity or selectivity of the catalyst.

21 cl, 2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a method for prolonged heterogeneously catalysed partial oxidation of propene to acrylic acid in gaseous phase, in which the initial gaseous reaction mixture 1, containing propene, molecular oxygen and at least one inert gas, where molecular oxygen and propene are in molar ratio O2:C3H6≥1, is first passed through a fixed catalyst bed 1 at high temperature at the first stage of the reaction, where the active mass of the catalysts is at least one multimetal oxide, containing molybdenum and/or tungsten, as well as at least one element from a group consisting of bismuth, tellurium, antimony, tin and copper, so that, conversion of propene in a single passage is ≥93 mol % and associated selectivity of formation of acrolein, as well as formation of acrylic acid by-product together is ≥90 mol %, temperature of the product gaseous mixture 1 leaving the first reaction stage is reduced if necessary through direct and/or indirect cooling, and if necessary, molecular oxygen and/or inert gas is added to the product gaseous mixture 1, and after that, the product gaseous mixture 1, acting as initial reaction mixture 2, which contains acrolein, molecular oxygen and at least one inert gas, where molecular oxygen and acrolein are in molar ratio O2:C3H4O≥0.5, is passed through a second fixed catalyst bed 2 at high temperature at the second reaction stage, where the active mass of the catalysts is at least one multimetal oxide, containing molybdenum and vanadium so that, conversion of acrolein in a single passage is ≥90 mol % and selectivity of the resultant formation of acrylic acid at both stages is ≥80 mol % in terms of converted propene, and temperature of each fixed catalyst bed is increased independently of each other. Partial oxidation in gaseous phase is interrupted at least once and at temperature of fixed catalyst bed 1 ranging from 250 to 550°C and temperature of fixed catalyst bed 2 ranging from 200 to 450°C, gaseous mixture G, which consists of molecular oxygen, inert gas and water vapour if necessary, is first passed through fixed catalyst bed 1, and then, if necessary, through an intermediate cooler and then finally through fixed catalyst bed 2, in which at least a single interruption takes place before temperature of the fixed catalyst bed 2 increases by 8°C or 10°C, wherein prolonged increase of temperature by 8°C or 10°C, is possible when virtual passage of temperature of the fixed catalyst bed in the period of time on the leveling curve running through the measuring point using the Legendre-Gauss method of the least sum of squares of errors, temperature increase of 7°C or 10°C is achieved.

EFFECT: method increases service life of catalyst.

24 cl, 1 ex, 3 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to improvement of the method of producing (meth)acrylic acid or (meth)acrolein through gas-phase catalytic oxidation of at least one oxidisable substance, chosen from propylene, propane, isobutylene and (meth)acrolein, molecular oxygen or a gas, which contains molecular oxygen, using a multitubular reactor, with such a structure that, there are several reaction tubes, with one (or several) catalytic layer (catalytic layers) in the direction of the axis of the tube, and a coolant can flow outside the said reaction tubes so as to regulate temperature of reaction, in which temperature of the said reaction of gas-phase catalytic oxidation is increased by varying temperature of the coolant at the inlet for regulating temperature of the reaction, while (1) temperature of coolant at the inlet for regulating temperature of the reaction is varied by not more than 2°C for each variation as such, and (2) when variation is done continuously, the time interval from the variation operation, directly preceding the present, is not more than 10 minutes, and, in addition, the difference between the maximum value of peak temperature of reaction of the catalyst layer of the reaction tube and temperature of the coolant at the inlet for regulating temperature of reaction is not less than 20°C.

EFFECT: method in which sharp increase of temperature is suppressed even after changing reaction conditions with aim of increasing temperature for improving efficiency, thus preventing catalyst deactivation, and achieving stable output.

3 cl, 5 dwg, 5 ex

FIELD: chemistry.

SUBSTANCE: invention relates to improved method of carrying out heterogenous catalytic partial oxidation in gas phase of acrolein into acrylic acid, during which reaction gas mixture, containing acrolein, molecular oxygen and at least one inert gas-thinner, is passed through having higher temperature catalytic still layer, whose catalysts are made in such way that their active mass contains at least one oxide of multimetal, containing elements Mo and V, and in which during time, temperature of catalytic still layer is increased, partial oxidation in gas phase being interrupted at least once and at temperature of catalytic still layer from 200 to 450°C acrolein-free, containing molecular oxygen, inert gas and, if necessary, water vapour, as well as, if necessary, CO, gas mixture of G oxidative action is passed through it, at least one interruption being performed before increase of catalytic still layer temperature constitutes 2°C or 4°C or 8°C or 10°C during a long period of time, temperature increase constituting 2°C or 4°C or 8°C or 10°C over a long period of time occurring when in plotting factual course of temperature of catalytic still layer during time on laid through measurement points equation curve according to elaborated by Legendre and Gauss method of the least sum of error squares 2°C or 4°C or 8°C or 10°C temperature increase is achieved.

EFFECT: ensuring spread of hot point with time which is less than in previous methods.

21 cl, 3 dwg, 1 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of producing (met)acrolein and/or (met)acrylic acid through heterogeneous catalytic partial oxidation in gaseous phase, in which a fresh fixed-bed catalyst at 100-600°C in a reactor is loaded with a mixture of loading gas, which along with at least, one C3/C4 organic precursor compound subject to partial oxidation and oxidation with molecular oxygen, contains at least one gas-diluent. The process is carried out after establishing content of the mixture of loading gas at constant conversion of organic precursor compound and at constant content of the mixture of loading gas initially in the input period for 3-10 days with load of 40-80% of higher final load, and then at higher filling load of the catalyst with a mixture of loading gas. In the input period, maximum deviation of conversion of organic precursor compound from arithmetic time-averaged and maximum deviation of the volume ratio of one component of the mixture loading gas, oxidising agent, organic precursor compound and gas-diluent, from the arithmetic time-averaged volume ratio of the corresponding component of the mixture of loading gas should not exceed ±10% of the corresponding arithmetic mean value.

EFFECT: method allows for eliminating shortcomings of previous technical level.

3 cl, 1 ex

FIELD: chemistry.

SUBSTANCE: invention concerns aggregate for (met)acrylic acid obtainment, including: reactor for (met)acrylic acid obtainment by catalytic gas phase oxidation reaction of one, two or more source compounds including propane, propylene, isobutylene and (met)acrolein, in gas mix of source substances including one, two or more source compounds including propane, propylene, isobutylene and (met)acrolein, and oxygen; heat exchanger connected to reactor and intended for cooling of reaction gas mix including obtained (met)acrylic acid; and absorption column connected to heat exchanger and intended for contact absorbing fluid with reaction gas mix for (met)acrylic acid absorption, so that (met)acrylic acid is absorbed from reaction gas mix by absorbing fluid. Additionally the aggregate includes: bypass pipe connecting reactor and absorption column without the use of intermediary heat exchanger; and device for flow rate adjustment in reaction gas flow passing through bypass pipe in order to maintain almost constant flow rate of gas mix feed of source materials to reactor or almost constant pressure of gas mix of source materials at the reactor inlet. Also invention concerns improved method of (met)acrylic acid obtainment by extraction of (met)acrylic acid absorbed by absorbing fluid.

EFFECT: heat power tapping from reaction gas mix, stable and continuous process even in case of heat exchanger intended for heat power extraction is blocked.

2 cl, 3 dwg, 1 ex

FIELD: chemistry.

SUBSTANCE: present invention pertains to improvement of the method of producing (met)acrylic acid or (met)acrolein using a multi-pipe reactor with a fixed bed. The reactor has several pipes, with at least one catalyst bed in the direction of the axis of the pipe. A heat carrier can regulate temperature outside the flow of the reaction pipe. In the reaction pipes, there is gas-phase catalytic oxidation of at least one type of oxidisable substance, propylene, propane, isobutylene and (met)acrolein by molecular oxygen or a gas, containing molecular oxygen. At the beginning of the process, the difference between the coolant temperature and the peak temperature of the catalyst is set in the interval 20-80°C, and during the process, peak temperature T(°C) of the catalyst in the direction of the axis of the pipe satisfies equation 1, given below: (equation 1), where L, T0, X and X0 stand for length of the reaction pipe, peak temperature of the catalyst in the direction of the axis of the pipe at the beginning of the process, the length up to the position which gives the peak temperature T at the input of the reaction pipe, and the length to the position which gives the peak temperature T0 at the input of the reaction pipe, respectively.

EFFECT: method allows for stable output of the target product, with high output for a long period of time, without reduction of catalyst activity.

3 dwg, 2 ex

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to the improved method for preparing acrylic acid and selective oxidation of propylene to acrolein. Method involves carrying out reaction of propylene with oxygen in the first zone reaction with the first catalyst corresponding to the following formula: AaBbCcCadFeeBifMo12Ox wherein A means Li, Na, K, Rb and Cs and their mixtures also; B means Mg, Sr, Mn, Ni, Co and Zn and their mixtures also; C means Ce, Cr, Al, Sb, P, Ge, Sn, Cu, V and W and their mixtures also wherein a = 0.01-1.0; b and e = 1.0-10; c = 0-5.0 but preferably 0.05-5.0; d and f = 0.05-5.0; x represents a number determined by valence of other presenting elements. Reaction is carried out at enhanced temperature providing preparing acrylic acid and acrolein and the following addition of acrolein from the first reaction zone to the second reaction zone containing the second catalyst used for conversion of acrolein to acrylic acid. Method provides high conversion of propylene to acrylic acid and acrolein.

EFFECT: improved preparing method.

7 cl, 1 tbl, 5 ex

FIELD: chemistry.

SUBSTANCE: invention discloses a method for safe continuous heterogeneous catalysed gas-phase partial oxidation of at least one organic starting compound in a reactor, whose stream of loaded gas mixture along with at least one partially oxidisable organic starting compound and molecular oxygen as an oxidising agent contains at least one diluting gas which remains essentially inert under heterogeneous catalysed gas-phase partial oxidation conditions,and is obtained by merging at least two different initial streams, where through online measurement of concentration of one or more selected components in the stream of the loaded gas mixture in one or more initial streams which form the stream of the loaded gas mixture and/or stream of gas mixture of the product, loading of an uncontrolled stream of gas mixture in terms of explosion risk or other is prevented, wherein for online measurement of the partial stream, the analysed gas stream is accordingly continuously fed into the measurement cell of an analysing device and during measurement, said stream comes out of the measurement cell into the free atmosphere, where the analysed gas stream and/or free atmosphere are subject to pressure fluctuations, where the effect of pressure fluctuation of the analysed gas stream and/or free atmosphere on the measured pressure in the measurement cell in the analysing device and therefore on the measurement resulta) is corrected through calculation, based on properties capable of correlation with the gas in the measurement cell and/or b) is minimised based on that the measured in the measurement cell of the analysing device is kept constant or controlled to a constant value using a pressure regulator, independent of the pressure of the analysed gas stream and/or free atmosphere.

EFFECT: high reliability and safety of the process.

18 cl, 4 ex, 1 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of producing acrylic acid from propylene, involving a first step where propylene is oxidised to acrolein and a second step where acrolein is oxidised to acrylic acid, as well as a step for dehydrating glycerin to acrolein in the presence of a propylene-containing gas. The said step for dehydrating glycerin is carried out before catalytic oxidation of propylene to acrolein in the presence of the supplied propylene-containing gas, or after catalytic oxidation of propylene to acrolein in the presence of a gaseous mixture coming out after oxidation of propylene to acrolein.

EFFECT: method enables partial use of renewable material, while increasing output of acrylic acid.

8 cl, 5 dwg, 6 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of producing acrylic acid from propylene, involving a first step where propylene is oxidised to acrolein and a second step where acrolein is oxidised to acrylic acid, as well as a step for dehydrating glycerin to acrolein in the presence of a propylene-containing gas. The said step for dehydrating glycerin is carried out before catalytic oxidation of propylene to acrolein in the presence of the supplied propylene-containing gas, or after catalytic oxidation of propylene to acrolein in the presence of a gaseous mixture coming out after oxidation of propylene to acrolein.

EFFECT: method enables partial use of renewable material, while increasing output of acrylic acid.

8 cl, 5 dwg, 6 ex

FIELD: chemistry.

SUBSTANCE: in accordance with the method A) at least two propane-containing gas supply streams are fed into the first reaction zone A, where at least one of the said streams contains fresh propane, and propane fed into this reaction zone undergoes heterogeneous catalytic dehydrogenation with a fixed bed catalyst, obtaining a propane- and propylene-containing gaseous mixture of products A, B) which is extracted from reaction zone A, in the first separation zone, A is separated from at least a portion of components contained in it, which are different from propane and propylene, and the remaining gaseous mixture of products A' which contains propane and propylene C) is used in the second reaction zone B for supplying at least one oxidation reactor, and propylene contained in the gaseous mixture of products A' in at least one oxidation reactor undergoes heterogeneous catalytic two-step gas-phase partial oxidation with molecular oxygen to acrylic acid or a mixture of acrolein and acrylic acid as an end product, as well as to an excess molecular oxygen-containing gaseous mixture of products B, D) which is extracted from the reaction zone B, in the second separation zone B, the end product contained in it is extracted through absorption or fractional condensation, and at least a portion of the remaining residual gas which contains unconverted propane, molecular oxygen, and also if necessary, unconverted propylene are recycled into the reaction zone A as at least one of two propane-containing supply streams, where the said recycling into the reaction zone A is done along the path of the heterogeneous catalysed dehydrogation of propane in that reaction zone such that, at the point for feeding the recycled gas into reaction zone A at least 5 mol % of propane has already undergone dehydrogenation, where the said propane is fed into this reaction zone with other supply streams, where molar ratio of the propylene contained in the reaction gaseous mixture to molecular hydrogen contained in the said mixture within the reaction zone A does not exceed 10.

EFFECT: design of an improved method of obtaining acrolein, acrylic acid or their mixture from propane.

41 cl, 3 ex

FIELD: chemistry.

SUBSTANCE: in accordance with the method A) at least two propane-containing gas supply streams are fed into the first reaction zone A, where at least one of the said streams contains fresh propane, and propane fed into this reaction zone undergoes heterogeneous catalytic dehydrogenation with a fixed bed catalyst, obtaining a propane- and propylene-containing gaseous mixture of products A, B) which is extracted from reaction zone A, in the first separation zone, A is separated from at least a portion of components contained in it, which are different from propane and propylene, and the remaining gaseous mixture of products A' which contains propane and propylene C) is used in the second reaction zone B for supplying at least one oxidation reactor, and propylene contained in the gaseous mixture of products A' in at least one oxidation reactor undergoes heterogeneous catalytic two-step gas-phase partial oxidation with molecular oxygen to acrylic acid or a mixture of acrolein and acrylic acid as an end product, as well as to an excess molecular oxygen-containing gaseous mixture of products B, D) which is extracted from the reaction zone B, in the second separation zone B, the end product contained in it is extracted through absorption or fractional condensation, and at least a portion of the remaining residual gas which contains unconverted propane, molecular oxygen, and also if necessary, unconverted propylene are recycled into the reaction zone A as at least one of two propane-containing supply streams, where the said recycling into the reaction zone A is done along the path of the heterogeneous catalysed dehydrogation of propane in that reaction zone such that, at the point for feeding the recycled gas into reaction zone A at least 5 mol % of propane has already undergone dehydrogenation, where the said propane is fed into this reaction zone with other supply streams, where molar ratio of the propylene contained in the reaction gaseous mixture to molecular hydrogen contained in the said mixture within the reaction zone A does not exceed 10.

EFFECT: design of an improved method of obtaining acrolein, acrylic acid or their mixture from propane.

41 cl, 3 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a single-step method for vapour-phase oxidation of an alkane such as propane which leads to production of unsaturated caboxylic acid such as acrylic or methacrylic acid in the presence of a mixed metal oxide catalyst and excess alkane with respect to amount of oxygen. The method of producing unsaturated carboxylic acid involves: (a) reacting alkane and oxygen-containing gas in a reaction zone with a catalyst which contains mixed metal oxide under conditions which enable production of a gaseous product containing unsaturated carboxylic acid, unreacted alkane and an alkene by-product; (b) extraction of unreacted alkane and alkene by-product from the gaseous product; and (c) recycling the mixture of the extracted unreacted alkane and alkene by-product to the reaction zone without separating components; in which the mixed metal oxide consists of material with general formula MoVvAaBbCcOx where Mo is molybdenum, V is vanadium, each of A, B and C represents niobium, antimony, tellurium, silver, tantalum, titanium, aluminium, zirconium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, platinum, bismuth, boron, indium, arsenic, germanium, tin, lithium, sodium, potassium, rubidium, caesium, francium, beryllium, magnesium, calcium, stronium, barium, hafnium, lead, phosphorus, promethium, europium, gadolinium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, gold, selenium, palladium, gallium, zinc, praseodymium, rhenium, iridium, neodymium, yttrium, samarium and terbium, v equals 0.1-0.5, a equals 0.01-0.2, b equals 0.0-0.5, c equals 0.0-0.5, value of x is determined by valency of other components, in which alkane is propane or isobutane; where the alkane is in excess relative oxygen and molar ratio alkane: oxygen ranges from 3:1 to 1:1; and in which amount of alkene recycled to the reactor corresponds to the molar ratio alkane: alkene equal to 1:0.03-1:0.1.

EFFECT: improved method.

14 cl, 3 tbl, 1 dwg, 23 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of continuous, heterogeneous, catalytic, partial gas-phase oxidation of at least one organic compound selected from a group comprising propene, acrolein, isobutene, methacrolein, isobutene and propane, in an oxidation reactor loaded with a gas mixture which, along with at least one compound to undergo partial oxidation and molecular oxygen as an oxidation agent, includes at least one diluent gas which is essentially inert in conditions of heterogeneous, catalytic, gas-phase partial oxidation, where the source of oxygen and inert gas for the loaded gas mixture is air which is compressed in a compressor beforehand from a low initial pressure value to a high final pressure value, where before entering the compressor, the air undergoes at least one mechanical separation procedure through which particles of solid substance dispersed in the air can be separated.

EFFECT: method prevents negative effect of solid particles on the air compression stage, undesirable increase in pressure loss and reduction of activity or selectivity of the catalyst.

21 cl, 2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of producing butylacrylate involving: reaction of acrylic acid with butanol in the presence of water and a catalyst in a reactor; where the starting material is an aqueous solution of acrylic acid which is at least one of: (1) condensed water, obtained from vapour used in a kinetic vacuum pump which transports gas after trapping fluid process medium- vapour which is blown at high speed, (2) water for hydraulic sealing in a liquid ring pump which isolates liquid-water after air is let into the housing, (3) water used for collecting acrylic acid in the device which collects acrylic acid from an acrylic acid-containing gas, and acrylic acid which is not present in the aqueous solution of acrylic acid, where the device used for collecting acrylic acid is one or more devices selected from a group comprising a packed column, a plate-type column, a spray column and a scrubber. The invention also relates to a method of producing a super-absorbing polymer based on acrylic acid, involving the following steps: polymerisation of acrylic acid, in which the aqueous phase used is an emulsified aqueous solution of an acrylic acid monomer and water, dehydration of the obtained mixture during azerotropic distillation, where the starting material is aqueous acrylic acid solution which is at least one of the following: condensed water obtained from vapour used in a kinetic vacuum pump which transports gas after trapping fluid process medium - vapour, which is blown at high speed, water for hydraulic sealing in a liquid ring pump which isolates liquid-water after air is let into the housing, water used for collecting acrylic acid in the device which collects acrylic acid from an acrylic acid-containing gas, and acrylic acid which is not present in the aqueous solution of acrylic acid, where the device used for collecting acrylic acid is one or more devices selected from a group comprising a packed column, a plate-type column, a spray column and a scrubber.

EFFECT: design of an efficient method of using aqueous solution of (meth)acrylic acid with low concentration, formed at the stage for producing/storing (meth)acrylic acid.

13 cl, 2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a method for prolonged heterogeneously catalysed partial oxidation of propene to acrylic acid in gaseous phase, in which the initial gaseous reaction mixture 1, containing propene, molecular oxygen and at least one inert gas, where molecular oxygen and propene are in molar ratio O2:C3H6≥1, is first passed through a fixed catalyst bed 1 at high temperature at the first stage of the reaction, where the active mass of the catalysts is at least one multimetal oxide, containing molybdenum and/or tungsten, as well as at least one element from a group consisting of bismuth, tellurium, antimony, tin and copper, so that, conversion of propene in a single passage is ≥93 mol % and associated selectivity of formation of acrolein, as well as formation of acrylic acid by-product together is ≥90 mol %, temperature of the product gaseous mixture 1 leaving the first reaction stage is reduced if necessary through direct and/or indirect cooling, and if necessary, molecular oxygen and/or inert gas is added to the product gaseous mixture 1, and after that, the product gaseous mixture 1, acting as initial reaction mixture 2, which contains acrolein, molecular oxygen and at least one inert gas, where molecular oxygen and acrolein are in molar ratio O2:C3H4O≥0.5, is passed through a second fixed catalyst bed 2 at high temperature at the second reaction stage, where the active mass of the catalysts is at least one multimetal oxide, containing molybdenum and vanadium so that, conversion of acrolein in a single passage is ≥90 mol % and selectivity of the resultant formation of acrylic acid at both stages is ≥80 mol % in terms of converted propene, and temperature of each fixed catalyst bed is increased independently of each other. Partial oxidation in gaseous phase is interrupted at least once and at temperature of fixed catalyst bed 1 ranging from 250 to 550°C and temperature of fixed catalyst bed 2 ranging from 200 to 450°C, gaseous mixture G, which consists of molecular oxygen, inert gas and water vapour if necessary, is first passed through fixed catalyst bed 1, and then, if necessary, through an intermediate cooler and then finally through fixed catalyst bed 2, in which at least a single interruption takes place before temperature of the fixed catalyst bed 2 increases by 8°C or 10°C, wherein prolonged increase of temperature by 8°C or 10°C, is possible when virtual passage of temperature of the fixed catalyst bed in the period of time on the leveling curve running through the measuring point using the Legendre-Gauss method of the least sum of squares of errors, temperature increase of 7°C or 10°C is achieved.

EFFECT: method increases service life of catalyst.

24 cl, 1 ex, 3 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to improvement of the method of producing (meth)acrylic acid or (meth)acrolein through gas-phase catalytic oxidation of at least one oxidisable substance, chosen from propylene, propane, isobutylene and (meth)acrolein, molecular oxygen or a gas, which contains molecular oxygen, using a multitubular reactor, with such a structure that, there are several reaction tubes, with one (or several) catalytic layer (catalytic layers) in the direction of the axis of the tube, and a coolant can flow outside the said reaction tubes so as to regulate temperature of reaction, in which temperature of the said reaction of gas-phase catalytic oxidation is increased by varying temperature of the coolant at the inlet for regulating temperature of the reaction, while (1) temperature of coolant at the inlet for regulating temperature of the reaction is varied by not more than 2°C for each variation as such, and (2) when variation is done continuously, the time interval from the variation operation, directly preceding the present, is not more than 10 minutes, and, in addition, the difference between the maximum value of peak temperature of reaction of the catalyst layer of the reaction tube and temperature of the coolant at the inlet for regulating temperature of reaction is not less than 20°C.

EFFECT: method in which sharp increase of temperature is suppressed even after changing reaction conditions with aim of increasing temperature for improving efficiency, thus preventing catalyst deactivation, and achieving stable output.

3 cl, 5 dwg, 5 ex

FIELD: chemistry.

SUBSTANCE: invention discloses a method for safe continuous heterogeneous catalysed gas-phase partial oxidation of at least one organic starting compound in a reactor, whose stream of loaded gas mixture along with at least one partially oxidisable organic starting compound and molecular oxygen as an oxidising agent contains at least one diluting gas which remains essentially inert under heterogeneous catalysed gas-phase partial oxidation conditions,and is obtained by merging at least two different initial streams, where through online measurement of concentration of one or more selected components in the stream of the loaded gas mixture in one or more initial streams which form the stream of the loaded gas mixture and/or stream of gas mixture of the product, loading of an uncontrolled stream of gas mixture in terms of explosion risk or other is prevented, wherein for online measurement of the partial stream, the analysed gas stream is accordingly continuously fed into the measurement cell of an analysing device and during measurement, said stream comes out of the measurement cell into the free atmosphere, where the analysed gas stream and/or free atmosphere are subject to pressure fluctuations, where the effect of pressure fluctuation of the analysed gas stream and/or free atmosphere on the measured pressure in the measurement cell in the analysing device and therefore on the measurement resulta) is corrected through calculation, based on properties capable of correlation with the gas in the measurement cell and/or b) is minimised based on that the measured in the measurement cell of the analysing device is kept constant or controlled to a constant value using a pressure regulator, independent of the pressure of the analysed gas stream and/or free atmosphere.

EFFECT: high reliability and safety of the process.

18 cl, 4 ex, 1 dwg

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