Method for preparing acrolein or acrylic acid or their mixture from propane

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to an improved method for synthesis of acrolein or acrylic acid or their mixture. Method involves at step (A) propane is subjected for partial heterogenous catalyzed dehydrogenation in gaseous phase to form a gaseous mixture A of product comprising molecular hydrogen, propylene, unconverted propane and components distinct from propane and propene, and then from a gaseous mixture of product from step (A) distinct from propane and propylene at least partial amount of molecular hydrogen is isolated and a mixture obtained after this isolation is used as a gaseous mixture A' at the second step (B) for loading at least into one oxidation reactor and in at least one oxidation reaction propylene is subjected for selective heterogenous catalyzed gas-phase partial oxidation with molecular oxygen to yield as the end product of gaseous mixture B containing acrolein or acrylic acid, or their mixture, and the third (C) wherein in limits of partial oxidation of propylene at step (B) of gaseous mixture B acrolein or acrylic acid or their mixtures as the end product are separated and at least unconverted propane containing in gaseous mixture at step (B) is recovered to the dehydrogenation step (A) wherein in limits of partial oxidation of propylene at step (B) molecular nitrogen is used as additional diluting gas. Method provides significant decreasing of by-side products.

EFFECT: improved method of synthesis.

39 cl, 11 ex

The invention relates to a method of producing acrolein, or acrylic acid, or mixtures thereof from propane, in which

A) in the first stage And the propane is subjected to partial, heterogeneous catalyzed dehydration in the gas phase with the formation of the gas mixture And the product containing molecular hydrogen, propylene and not converted propane,

B) from the containing molecular hydrogen, propylene and not converted propane gas mixture And the product stage And contained therein other than propane and propylene components separate at least a partial quantity of molecular hydrogen and use it as a gas mixture a', the second study In to boot, at least one oxidation reactor in at least one reactor for the oxidation of propylene is subjected to selective, heterogeneous catalyzed gas-phase partial oxidation with molecular oxygen to obtain the target product gas mixture containing acrolein or acrylic acid or their mixtures, and

(C) from received within the partial oxidation of propylene on stage In the gas mixture In the third stage To separate the target product and at least contained in the gas mixture phase In not converted propane return to the stage dehydrogenation A.

Acrylic acid is having the m is a great value basic chemical reagent, which is used, among other things, as a monomer for polymerization that, for example, being in dispersal distribution in the aquatic environment, used as a binder. Acrolein is an important intermediate product, for example, to get glutar-dialdehyde, methionine, folic acid and acrylic acid.

From such publications as EP-A 117 146, DE-A 3313573 and US-A 3161670, there is a method of conversion of propane to acrolein and/or acrylic acid (hereinafter referred to only in EP-A 117146).

At the first stage of the method, the propane is subjected to heterogeneous catalyzed partial dehydration in the gas phase with obtaining propylene. The resultant propylene in the second stage of the method is subjected to heterogeneous catalyzed, gas phase, partial oxidation of obtaining acrolein and/or acrylic acid. Hallmark is known from EP-A 117146 method is the fact that located along with propylene in the gas mixture of the dehydrogenation of propane basic components, such as molecular hydrogen, are inert with respect to the subsequent heterogeneous catalyzed gas-phase oxidation of propylene, so that the gas mixture of the dehydrogenation of propane according to EP-A 117146 without significant drawbacks, it is possible to transfer to the next stage of okelani is propylene, and of inert components at least unreacted propane may return to the stage dehydrogenation of propane.

In the publication DE-A 19508558 the method according to EP-A 117146 listed as having disadvantages as it use other than propane inert diluting gases in the second stage of the method according to EP-A 117146 is not profitable. A distinctive feature of the method according to DE-A 19508558 is that from the gas mixture of the first stage of the method according to EP-A 117146 before its further use in the second stage separates at least molecular hydrogen and water vapor as the oxygen source for the second stage used pure oxygen.

As a result of intensive studies, it was found that proposed in DE-A 19508558 way to his second stage leads to increased formation of by-product Propionaldehyde. This is a disadvantage (see, for example, publication of Japanese Laid Open Patent Application No. H11-35519), since saturated partial side products₃-oxidation can, on the one hand, only with difficulty be separated from the α,β-ethylene unsaturated partial target products₃-oxidation due to their chemical similarity, and, on the other hand, due to their unpleasant odor already in the slightest shares when their sales are faced with great difficulties.

The task of nastoyascheevremya therefore, is to develop a superior method compared to what is known from EP-A 117146, as well as from DE-a 19508558 ways.

Known for example from DE-A 19837517, DE-A 19837519, also DE-A 19837520 ways in which heterogeneous phase, catalyzed partial dehydrogenation replaced by homogeneous and/or catalyzed partial oxidisation not satisfactory (although rezultirase the mixture of the dehydrogenation does not contain hydrogen), is already in phase dehydrogenation they require significant amounts of molecular oxygen.

In line with this, developed a method of obtaining acrolein, or acrylic acid, or mixtures thereof, in which

A) in the first stage And the propane is subjected to partial, heterogeneous catalyzed dehydration in the gas phase with the formation of the gas mixture And the product containing molecular hydrogen, propylene and not converted propane and other than propane and propene components

B) from the containing molecular hydrogen, propylene and not converted propane gas mixture And the product stage And contained therein other than propane and propylene components separate at least a partial quantity of molecular hydrogen and use it as a gas mixture a', the second study In to boot, at least one oxidation reactor in at least one reactor for the oxidation of propylene selectively expose the, heterogeneous catalyzed gas-phase partial oxidation with molecular oxygen to obtain the target product gas mixture containing acrolein or acrylic acid, or mixtures thereof, and

(C) from received within the partial oxidation of propylene on stage In the gas mixture In the third stage To separate the target product and at least contained in the gas mixture phase In not converted propane return to the stage dehydrogenation And,

which is characterized by the fact that in the framework of partial oxidation of propylene on stage In applied molecular nitrogen as optionally the diluent gas.

Thus, while on the known from DE-A 19508558 stage of oxidation is served In the boot gas, which consists mainly of propylene, molecular oxygen and propane, according to the invention at the stage of oxidation is served In the boot gas, which contains propylene, molecular oxygen, propane and molecular nitrogen. The choice of the above components, the boot of the gas mixture phase oxidation ensures that in the framework of the method according to the invention not only applies blend boot gas phase oxidation, the limiting oxygen concentration (on this issue see the publication DE-A 19508558) in full may be satisfactory, but that one is temporarily it allows a reduction in the formation of undesirable side products, namely Propionaldehyde and/or propionic acid.

Needless to say, a mixture of boot gas phase oxidation In the method according to the invention can along with the already described components can additionally contain other components, such as CO, CO₂H₂O, noble gases such as helium and/or argon, hydrogen, methane, ethylene, ethane, butane, butene, Boutin, pentane, propyne, allene and/or acrolein. As a rule, the proportion of molecular nitrogen in the boot of the gas mixture phase oxidation In the terms contained in this boot gas mixture of propylene should not be according to the invention is below 5 mol.%. This means that when the method according to the invention, the proportion of molecular nitrogen in the boot of the gas mixture phase oxidation in terms of contained amount of propylene may be at least 10 mol.%, or at least 5 mol.%, or at least 20 mol.%, or at least 25 mol.%, or at least 50 mol.%, or at least 100 mol.%, or at least 200 mol.%, or at least 500 mol.%, or at least 750 mol.%, or at least 1000 mol.%. In the normal case, the value contained in the boot of the gas mixture phase oxidation In a molar amount of molecular nitrogen contained in the boot of the gas mixture phase oxidation In a molar quantity is and propylene is however, ≤40:1, often ≤30:1, in many cases, ≤20:1, and often ≤10:1. Preferred is a solution in which the molecular proportion of nitrogen in the boot of the gas mixture phase oxidation in terms of the amount of propylene is from 600 mol.% up to 1600 mol.%.

The molar ratio of the number contained in the boot of the gas mixture phase oxidation of molecular nitrogen to the quantity contained in the boot of the gas mixture phase oxidation of propane according to the invention is usually not less than 0.05. In the normal case, this ratio may be higher than five. Thus, the molar ratio of the number contained in the boot of the gas mixture phase oxidation of molecular nitrogen to the quantity contained in the boot of the gas mixture phase oxidation of propane may be from 0.05 to 5, or from 0.1 to 4, or from 0.5 to 3, or from 1 to 2.5, or about 2.

Often, when the method according to the invention the composition of the boot of the gas mixture phase oxidation In choose so that you will do the following molar ratio:

propane:propene:N₂:O₂:H₂O:procee

= 0.5 to 20:1:0.1 to 40:0.1 to 10:0 to 20:0 to 1.

Preferably, the above molar ratios are according to the invention

= 2 to 10:1:0.5 to 20:0.5 to 5:0.01 to 10:0 to 1.

It is also expedient if the cm is installed molar ratio is = 3 to 6:1:1 to 10:1 to 3:0.1 to 2:0 to 0.5.

The essential feature of the method according to the invention is that the gas mixture And the stage And unlike the case of homogeneous and/or heterogeneous catalyzed oxidation of propane contains molecular hydrogen, and that before applying the gas mixture And to download at least one oxidation reactor stage of the gas mixture And unlike described in the publication EP-A 117146 way to separate at least a partial amount of molecular hydrogen and in contrast to the method according to the publication DE-A 19508558 to reduce the formation of these side products, such as Propionaldehyde and/or propionic acid, replace it with molecular nitrogen.

Generally, the method according to the invention the molar ratio contained in the gas mixture And propylene contained in the gas mixture And the molecular hydrogen is ≤100, usually ≤75 often ≤50, in many cases, ≤40, in most cases ≤30 or ≤25, or ≤20.

Thus, according to the proposed method the molar ratio contained in the gas mixture And propylene contained in the gas mixture And the molecular hydrogen is ≤15, or ≤10 or ≤5 or ≤3, or ≤2 or ≤1.

In the normal case, the inverse value of the above ratio does not exceed 20.

Thus, conventional znacheniyami ratio contained in the gas mixture And propylene contained in the gas mixture And the molecular hydrogen is ≤ 0,05, in most cases ≤0,025 often ≤0,1, mainly ≤0,25, in many cases, ≤0,5, or ≤0,75 or ≤0,9.

To achieve on stage And when conducted according to the invention the partial heterogeneous catalyzed dehydrogenation high output in terms of a single pass, as a rule, it is necessary to operate at relatively high temperatures (in the typical case, these temperatures are from 300°700°). Due to the fact that the dehydrogenation (cleavage of C-H) compared with cracking (splitting of C-C) kinetically poorly, it is carried out by selectively operating the catalysts. On the formed polymer molecule as a rule, formed one molecule of hydrogen as a by-product. Due to the selectively active catalyst, which is usually made so that they develop at the above temperatures (for example, when 600° (C) with the exception of oxygen typical dehydrogenation (at loads propane catalysts, for example, 1000 h^-1the yield of propylene, as a rule, is at least 30 mol.% in one passage in terms of used propane), by-products such as methane, ethylene and ethane, are formed only in small amounts.

Due to the fact that the dehydrogenation reaction takes place with increasing volume, the output signal is increased by reducing the partial pressure of the products. This is achieved in a simple way, for example by dehydration under reduced pressure and/or by blending in a mostly inert gaseous diluents, for example water vapor, which in the normal case is an inert dehydrogenation gas. Dilution water vapor causes as other advantages reduce coking of the used catalyst, since the water vapor reacts with the formed coke on the principle of coal gasification. In addition, the water vapor as the diluent gas may be used in the next stage of oxidation Century Water vapor can easily be separated partially or completely from the gas mixture (e.g., condensation), which allows for further use of the resulting gas mixture a' stage oxidation to increase the proportion to be applied according to the invention the diluent gas N₂. Thus according to the invention it is possible to apply the total quantity or partial quantity used according to the invention of molecular nitrogen for dilution at the stage of A. Further, suitable for stage And diluents are, for example, CO, CO₂such noble gases like No, Ne and Ar. All these diluents can be used as such or in the form of various mixtures on stage A. the Advantage of the agreement is but the invention is what is suitable for stage And thinners are usually also suitable for stage oxidation diluents. In General, the preferred inert at an appropriate stage of the diluents (i.e chemically changing less than 5 mol.%, preferably less than 3 mol.% and better still less than 1 mol.%). In principle, stage And according to the invention are suitable all known from the prior art dehydrogenation catalysts. They are divided roughly into two groups, namely those that are oxide (for example, chromium oxide and/or aluminum oxide), and those that consist of the besieged, as a rule, on the oxide carrier, usually of relatively noble metal (e.g. platinum).

Among other things, for the stage And of the method according to the invention can be applied to all dehydrogenation catalysts, which are described in these patent publications, as WO 99/46039, US-A 4,788,371, EP-705 136, WO 99/29420, US-A5220091, US-A 5430220, US-A 5877369, EP-A 117 146, DE-A 19 937 106, DE-A 19937105 and DE-A 19 937 107. In particular, for all described in this publication as suitable for stage And according to the invention variants dehydrogenation can be used as catalyst of example 1 and example 2, and example 3 and example 4 of DE-A 19937107. When it comes to the dehydrogenation catalysts which contain from 10 to 99.9 wt.% zirconocene, from 0 to 60 wt.% the aluminum oxide is I, silicon dioxide and/or titanium dioxide and from 0.1 to 10 wt.% at least one element of the first or second main group, one element of the third side of the group, one element of the eighth side group of the periodic system of elements, Latin and/or tin, provided that the sum of the percents is equal to 100%.

For the implementation stage And method according to the invention is in principle suitable all known from the prior art reactor types and variants of the method. Descriptions of these variants of the method include, for example, all described in connection with the dehydrogenation catalysts known publication.

A relatively detailed description suitable for the method according to the invention, a method of dehydrogenation also available in the publication "Catalytica^®Studies Division, Oxidative Dehydrogenation and Alternative Dehydrogenation Processes, Study Number 4192 OD, 1993, 430 Ferguson Drive, Mountain View, California, 94043-5272 USA.

Typical partial heterogeneous catalyzed dehydrogenation of propane is that it is endothermically. This means that required to adjust the reaction temperature heat (energy) must be wired or reaction gas from the beginning and/or during catalyzed dehydrogenation.

Next heterogeneous catalyzed dehydrogenation of propane due to the high desired reaction temperature is typically that in small amounts is two formed high-boiling organic compounds, until the carbon deposited on the surface of catalysts and inactivate them. To reduce such negative effects, as has already been said to be passing through the surface of the catalysts for the catalytic dehydrogenation at high temperature propane can be diluted with water vapor. Deposited carbon under these conditions, partially or completely destroyed by the principle of coal gasification.

Another possibility for removing deposited carbon compounds lies in the fact that the dehydrogenation catalyst from time to time rinse at high temperature oxygen-containing gas and at the same time as would separate the deposited carbon. Suppression of deposition of carbon is also possible due to the fact that the subject catalytic dehydrogenation of propane before it is passed at a high temperature through the catalyst dehydrogenation add molecular hydrogen.

Of course there is also the possibility to add water vapor and molecular hydrogen be catalyzed the dehydrogenation of propane in the mixture. The addition of molecular hydrogen to catalyzed the dehydrogenation of propane reduces also the undesirable formation of Allen and acetylene as by-products.

Suitable form of reactor for the stage And from which bretania is a tubular reactor with a fixed bed, accordingly, the sectional tubular reactor, i.e., the dehydrogenation catalyst is one or more partitions of the reaction tubes as a fixed layer. The reaction tubes are heated so that the outside of the reaction tube space is combusted gas, for example a hydrocarbon, such as methane. This direct form of contact heating pipes well to apply only approximately the first 20% to 30% bulk fixed layer and the remaining length of the bulk layer to heat to the desired reaction temperature released under the burning heat. Thus, it can be achieved approximately isothermal mode of reaction. Suitable inner diameter of the reaction tube diameters are from 10 to 15 see Typical dehydrogenation reactor with sectional pipe includes from 300 to 1000 reaction tubes. The temperature inside the reaction pipe is in the range from 300°700°C, preferably from 400°700°C. Mainly the reaction gas is supplied to the tubular reactor preheated to the reaction temperature. Often the reaction mixture leaves the reactor at a temperature lying in 50-100°below. In the framework of the described method, the appropriate use of oxide dehydrogenation catalysts based on chromium oxide and/or aluminum. Often gas-RA is beviteli not apply, and as the source of the reaction gas, we take a pure propane. Also the dehydrogenation catalyst used in most cases undiluted.

In large industrial plants use approximately three parallel operated sectional tubular reactor, two reactors are typically in mode dehydrogenation, while in the same reactor to regenerate the catalyst loading.

The above method is applied, for example, known from various publications of the way dehydrogenation of propane BASF-Linda.

Further, this method is used when the so-called "proactive reforming" "steam active reforming (STAR) process, which was developed by Philips Petroleum. (see, for example, the publication US-A 4 902849, US-A 4996387 and US-A 5389342). As a dehydrogenation catalyst in such a reformer is used, containing the promoters spinel platinum on the tin (magnesium aluminate) as a carrier (see, for example, US-A 5073662). In contrast to the method of dehydrogenation of propane by BASF-Linda subject to dehydrogenation of propane when proactive reforming STAR diluted with water vapor. Typically, the molar ratio of water vapor to the propane in the range from 4 to 6. Working pressure often varies from 3 to 8 bar and the reaction temperature is selected expedient way from 480°620°C. Typical what recalls the total catalyst, the reaction gas mixture is from 0.5 to 10 h ^-1.

Needless to say, the stage of the way And according to the invention can be carried out in the movable layer. For example, the movable catalyst bed can be placed in the reactor with radial flow. In this reactor the catalyst is moving slowly from the top down, while the reaction gas mixture flows radially. This method is applied in the so-called method of dehydrogenation UOP-Oleflex. Due to the fact that the reactors in this way are in the adiabatic regime, it is reasonable consistent inclusion of multiple reactors (typically up to four). Consequently, it is possible to prevent too great a temperature difference between the reaction gas mixture at the inlet and at the outlet of the reactor (in the adiabatic mode, the output of the reaction gas mixture is a carrier of heat from the heat amount which depends on the reaction temperature) and in spite of this to ensure a good overall yield.

When the catalyst layer leaves the reactor with a moving bed, he served on the stage of the regenerate and then re-applied. As a dehydrogenation catalyst for this method can be used, for example, a spherical catalyst, which consists mainly of platinum on the spherical carrier of aluminum oxide. When the reactor type UOP variable propane dehydrogenation of personalit is camping hydrogen, to prevent premature aging of the catalyst. Working pressure ranges from 2 to 5 ATM. The ratio of hydrogen to propane (molar ratio) is expediently from 0.1 to 1. The reaction temperature is preferably from 550°650°and the load of the catalyst of the reaction gas mixture is selected from about 2 to 6 h^-1.

When the described method in a reactor with a fixed bed catalyst can be spherical, but it can also be cylindrical (hollow or solid).

As another option, the stage And according to the invention in the publication Proceedings De Witt, Petrochem. Review, Houston Texas, 1992 a, N1 describes the possibility of heterogeneous catalyzed propane dehydrogenation in a fluidized bed, in which the propane is not diluted.

Thus there are two located next to each other fluidized bed, one of which, typically, is in the state of the regenerate. As the active mass is thus suitable chromated aluminum oxide. Working pressure is from 1 to 1.5 ATM, and the temperature of the dehydrogenation is typically from 550°to 600°C. Required for the dehydrogenation heat is introduced into the reaction system due to the fact that the dehydrogenation catalyst is preheated to the reaction temperature, the work is its pressure, as a rule, is from 1 to 2 ATM, and the temperature is preferably from 550°to 600°C. This method of dehydrogenation known in the literature as a way of Saporetti-Artinez.

Alternative to the above methods stage And according to the invention can be developed by ABB Lummus Crest way (see publication Proceedings De Witt, Petrochem. Review, Houston Texas, 1992, P1).

Described are still heterogeneous catalyzed methods dehydrogenation of propane have in common that they are carried out by conversion of propane to >30 mol.% (usually in terms of single pass reactor).

The advantage according to the invention is that for the proposed method, it is sufficient if stage And achieved conversion of propane from ≥5 mol.% to ≤30 mol.% or ≤25 mol.%. I.e. stage And may be also carried out by conversion of the propane from 10 to 20 mol.% (conversion in terms of single pass reactor). This is due inter alia to the fact that the remaining amount of unreacted not converted propane at a later stage In the oxidation of diluted molecular nitrogen, which reduces the formation of Propionaldehyde and/or propionic acid as by-products.

To implement the conversion of propane is advisable to carry out the dehydrogenation of propane according to the invention at the stage And at an operating pressure of from 0.3 to ATM. Next, it is advisable to dilute digidrirovanny propane water vapor. The molar ratio of water vapor to be the dehydrogenation of propane is from 0.1 to 2. The heat capacity of water, on the one hand, allows to compensate a part of the endothermic dehydrogenation steps, and, on the other hand, razbivka steam reduces the partial pressure of the source and destination of the product, which is a positive effect on the equilibrium of the dehydrogenation. Further, the use of water vapor, as mentioned above, has a positive effect on the service life of the catalyst. If you need another component can be added molecular hydrogen. The molar ratio of molecular hydrogen to propane as a rule, is ≤5. In accordance with this molar ratio of molecular hydrogen to propane on stage And with relatively low conversion of propane can be from ≥0 to 30, expediently from 0.1 to 2 and preferably from 0.5 to 1. For a method with a low conversion of propane pre-emption is such a solution, in which a single pass reactor gas reaction consumes a relatively small amount of heat, and to achieve the conversion in a single pass reactor sufficient relatively low reaction temperature.

Therefore, according to the invention is suitable for the version with the stage And with a relatively low conversion of propane to propane dehydrogenation (quasi) o adiabatically. This means that the output gas mixture is typically heated to a temperature between 500°700°With (for example, by directly heating the circumferential wall), respectively, to a temperature of from 550°650°C. In the normal case, then sufficient single adiabatic passage through the catalyst layer to achieve the desired conversion, and the reaction gas mixture is cooled to from about 30°to 200°With (depending on conversion). The presence of water vapor as a carrier of heat has a positive effect on adiabatic mode. Low reaction temperature can achieve a longer life of the applied catalyst.

In principle, stage And according to the invention with comparatively low propane conversion can be carried out, whether it is o adiabatically or isothermal, as in a reactor with a fixed bed, or in a reactor with a moving or fluidized bed.

It should be noted that for the implementation of this stage, in particular, in the adiabatic regime sufficient to separate the reactor with the shaft furnace as a reactor with a fixed bed through which the reaction gas mixture flows axially and/or radially.

In the simplest case, we are talking about a single reaction tube, the internal diameter of which ranges from 0 to 10 m, in particular from 0.5 to 5 m and in which the fixed catalyst layer applied to the support device (for example, the grate). Through the loaded catalyst reaction tube, which in the adiabatic mode, insulated, axial flows hot, containing propane, the reaction gas. The catalyst may have a spherical or circular shape. In the preferred case, the catalyst can also be used in the form of rubble. For the implementation of the radial flow containing propane reaction gas to the reactor may consist of two located in the shell concentrically inserted into each other grate and catalyst filling is in their annular gap. In the adiabatic mode, the shell is thermally isolated.

As a catalyst loading for the stage And according to the invention with comparatively low propane conversion in a single pass is suitable, for example, described in the publication DE-A 19937107, first of all described in the examples, the catalysts.

After a long period of work described catalysts can be a simple way regenerated, and at a temperature of from 300 to 600°With, frequently from 400 to 500°With, in the first stage regenerating diluted with nitrogen air is passed over the catalyst layer. The loading of the catalyst with regeneration gas MozyPro to be for example, from 50 to 10000 h^-1and oxygen gas regeneration is from 0.5 to 20 vol.%.

At subsequent stages of regeneration under the same conditions as the regeneration gas may be air. From a technological point of view it is recommended to rinse the catalyst before it regenerierung inert gas (for example, N₂).

In conclusion, as a rule, it is recommended to perform regenerative still pure molecular hydrogen or diluted with an inert gas molecular hydrogen (hydrogen content should be ≥1 vol.%) in other respects under the same conditions.

Stage And according to the invention with comparatively low propane conversion (≤30 mol.%) in all cases, can be carried out under the same loads catalyst (as in General reaction gas, and contained propane), and options stage And with high conversion (>30 mol.%). This load reaction gas may be, for example, from 100 to 10000 h^-1often from 100 to 3000 h^-1i.e. in many cases from 100 to 2000 h^-1.

Particularly good implementation stage And according to the invention with comparatively low propane conversion in lattice reactor.

This reactor contains consistently more than one catalytic dehydrogenation catalizzatore what about the layer. The number of catalyst layers may be from 1 to 20, an expedient manner from 2 to 8, or from 4 to 6. Catalyst layers are preferably radially or axially one behind the other. In this lattice the reactor used is suitable for the technology follows a fixed catalyst layer.

In the simple case of performing the fixed catalyst layers in the reactor type shaft furnace are located axially or in the annular gaps placed concentrically in one another cylindrical arrays.

The reaction mixture is on the way from one catalyst layer to the next catalyst layer is subjected to intermediate heating in lattice reactor due to transmission through heated by hot gases fin heat exchangers and as a result of passing through the pipe, a hot-gas burning.

In that case, if the lattice of the catalyst used in the rest in the adiabatic regime, for the desired conversion of propane (≤30 mol.%), in particular, in the application described in DE-A 19937107 catalysts, in particular the preferred forms of execution, simply enter in the dehydrogenation reactor, the reaction mixture is preheated to a temperature of from 450°550°and to keep within the lattice of the reactor temperature in this range. Thus, the total dehydrogenation what should be carried out at extremely low temperatures, which is especially good for the life of the fixed catalyst layer.

Better to conduct the above-mentioned pre-heating direct way. To do this, to the reaction gas mixture or already before passing through the first catalyst layer and/or between following each other catalyst layers with molecular oxygen in a confined volume. Depending on the applied catalyst for the dehydrogenation thus achieved a limited combustion contained in the reaction gas mixture of hydrocarbons, if necessary, already deposited on the catalyst surface coal, respectively, of such compounds and/or formed during propane dehydrogenation and/or added to the reaction gas mixture of hydrogen, (may also be appropriate from the point of view of engineering applications introduction to lattice reactor catalyst layers, which are coated with catalyst, which specifically (selectively) catalyzes the combustion of hydrogen and/or hydrocarbon) (as such catalysts are suitable, for example, described in the publications US-A 4788371, US-A 4886928, US-A 5430209, US-A 55530171, US-A 5527979 and US-A 5563314 catalysts); for example, such catalyst layers in the alternative case can be placed alternately with containing the dehydrogenation catalyst layers in the region of setData reactor). The released heat of reaction allows quasi Autoterminal nearly isothermal heterogeneous dehydrogenation of propane. Increasing the selected temperature gas reactor may dehydrogenation of propane with declining and mostly contrasting temperature, which, in particular, results long service life of the catalyst.

As a rule, above the power of oxygen should be carried out in such a way that the oxygen content in the reaction gas mixture in terms of the contained amount of propane and propylene is from 0.5 to 10 vol.%. As the source of oxygen thus suitable as a pure molecular oxygen or diluted with an inert gas, such as CO, CO₂N₂noble gases oxygen and the oxygen of the air. Resultwise gas acts as additional dilution and contributes as a consequence, heterogeneous catalyzed dehydration.

The isothermic parameter heterogeneous catalyzed dehydrogenation of propane can be further improved by the fact that in lattice reactor in the spaces between the catalyst layers are placed closed, evacuated before filling in the application (e.g., tubular). Such installation needless to say can also be inserted in sootvetstvujushij catalysis is ornago layer. These contain built suitable solids or liquids that evaporate above a certain temperature or melt and consume the warmth and where the temperature is diminished, again condense and release heat.

One possibility of heating the reaction gas mixture phase And of the method according to the invention at the desired temperature of reaction is the combustion of part of the contained propane and/or N₂with the help of molecular oxygen (for example, on suitable operating specific combustion catalysts, for example, through a simple bypass and/or bandwidth) and heated using so released heat of combustion at the desired reaction temperature. Rezultiruja products of combustion, such as CO₂N₂O, and also may escort required for combustion with molecular oxygen to N₂form an inert gas diluent.

Essential for the invention is that applied at the stage And propane should not be pure propane. Used propane may contain up to 50% vol. other gases such as ethane, methane, ethylene, butane, butene, propyne, acetylene, H₂S, SO₂, pentane, etc. Used crude propane contains an expedient manner at least 60 vol.%, preferably at least 70 vol.%, advantage is the result of at least 80 vol.%, especially preferably at least 90 vol.% and particularly preferably at least 95 vol.% propane. In particular, for the stage And according to the invention can also be used a mixture of propane, propylene and from what is happening with the stage of oxidation of the recirculating gas.

Leaving in the framework of the method according to the invention phase And the gas mixture contains at least components propane, propene and molecular hydrogen. In addition, it contains, as a rule, the gases from the group comprising N₂H₂Oh, methane, ethane, ethylene, CO, and CO₂.

Typically, the reaction mixture has a pressure of from 0.3 to 10 ATM and a temperature of 400°550°With, in preferred cases from 450°500°C.

Essential to the method according to the invention is separating at least part of the contained in the mixture And hydrogen before the resulting gas mixture And' on stage is used to load the at least one oxidation reactor. This may be due to the fact that the gas mixture And, if necessary, after it is cooled in indirect heat exchanger (suitable way take this heat is used for heating necessary for the method according to the invention nutrients gas) flows, as a rule, made in the shape of a tube with a membrane that is permeable to molecular water is the genus. Separated thus molecular hydrogen is optionally partially returned to the stage And or served on other well-known application. In the simplest case it can be burned in fuel cells.

An alternative to that required at least partial separation of the hydrogen may also be parallel condensation, adsorption and/or by distillation (preferably under pressure).

Generally, according to the present invention is separated at least 10 mol.% or at least 25 mol.%, often at least 35 mol.% or at least 50 mol.%, in most cases, at least 75 mol.% and often all the amount contained in the gas mixture And molecular hydrogen before it is used as a gas mixture a' on stage for loading at least one oxidation reactor.

Needless to say, if necessary, in the Department of molecular hydrogen can be a Department other than propane and propylene, components of the gas mixture A.

The mere possibility of separating substantially all other than propane and propylene components of the gas mixture And is preferably cooled (preferably to a temperature of from 10°C to 70° (C) the gas mixture And, for example, at a pressure of from 0.1 to 50 ATM and a temperature of from 0° With up to 100°is brought into contact with (preferably high-boiling organic solvent (preferably hydrophobic), in which preferably adsorbed propane and propene (for example, a simple passing through the mixture). Through subsequent deformirovaniya, rectification and/or steam inert to oxidation steps In the invention of gas and/or molecular oxygen (e.g. air) propane and propene regenerate in the mixture and apply to load at least one oxidation reactor stage Century. Containing molecular hydrogen othonoi gas absorption can again be subjected to, for example, membrane separation, and then to apply the separated hydrogen at the stage A. Preferably the boiling point of the organic agent adsorption should be ≥100°S, particularly preferably ≥180°C. The adsorption can be carried out in columns, and the rotary adsorber. You can work as in the stream one direction and the opposite stream. Suitable absorption columns are, for example, column trays (with the cap, centrifuge and/or sieve plates), columns with structured packings (for example, sheet packings with a specific surface of from 100 to 500 m²/m³for example, Mellapak type^®250 Y) and Packed columns (the example with nozzles of the type Raschig). Needless to say, may be suitable irrigation columns and spray columns, graphite block absorbers, surface absorbers such as thick - or thin-layer adsorber, and rotary columns, plate scrubbers, centrifugal scrubbers and rotary scrubbers.

According to the invention gives the advantage of this embodiment in which you want to use organic adsorption agent, on the one hand, performs existing recommendations regarding boiling point, and on the other hand, at the same time are not too high molecular weight. Molecular weight agent adsorption is ≤300 g/mol.

With the essence of this proposal is that at the stage of partial oxidation using propane as well as using molecular nitrogen as an additional gas diluent.

By adding molecular nitrogen to the reaction mixture unexpectedly inhibited the formation of the above-mentioned unwanted side products of transformation used propane.

This technical result is not described and not available in the cited documents.

Suitable according to the invention the adsorption agents are, for example, a relatively non-polar organic solvents, which are preferably not with the keep acting out the polar group. As an example, it should lead aliphatic (for example, C₈to C₁₈-alkanes or aromatic hydrocarbons, for example, the average fraction distillation of paraffin, or ethers with bulky groups on the oxygen atom, or mixtures thereof, and to them may be added to a polar solvent, such as described in the publication DE-A4308087 1,2-dimethylphthalate. Further suitable esters of benzoic and talavou acid with unbranched, containing from 1 to 8 carbon atoms with alkanols, such as a complex n-butyl ester of benzoic acid, methyl ester benzoic acid, a complex of ethyl ether, dimethyl ether complex talavou acid diethyl ether complex talavou acid, and the so-called alonesee oils, such as diphenyl, diphenyl ether and mixtures of diphenyl and diphenyl ether and chlorinated and triarylamine, for example 4-methyl-4'-benzyl-diphenyl-methane and its isomers, 2-methyl-2'benzyldimethylamine, 2-methyl-4'-benzyl-diphenylethan and 4-methyl-2'-benzyl-difenilmetana and mixtures of such isomers. Suitable agent adsorption is a solvent mixture of diphenyl and diphenyl ether, preferably in the azeotropic composition. In particular, from 25 wt.% of diphenyl (biphenyl) and about 75 wt.% diphenyl ether, for example a commercially available Diphyl^®. This mixture of solvents cha is then contains the solvent, as dimethylphthalate, in the amount of from 0.1 to 25 wt.% in terms of the total amount of the mixture. With this as a possible agent adsorption should mention octane, nonanes, decanes, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane and octadecane.

In conclusion, we should indicate that partial complete separation of molecular hydrogen from the gas mixture And the product may be also carried out through selective, heterogeneous catalyzed combustion with molecular oxygen. Suitable catalysts are described, for example, in the publications US-A 4788371, US-A 4886928, US-And 5430209, US-A 55530171, US-A 5527979 and US-A 5563314.

After the incident, at least partial separation contained in the gas mixture And molecular hydrogen resulting gas mixture A' can be applied according to the invention in the second stage for loading at least one oxidation reactor and at least one reactor for selective propylene catalyzed gas-phase partial oxidation by molecular oxygen with a receipt containing acrolein and/or acrylic acid of the gas mixture C. If necessary, when this gas mixture A' by indirect heat exchange pre-heated to the desired in at least one oxidation reactor temperature is in the response.

In principle, heterogeneous catalyzed gas-phase partial oxidation of propylene with obtaining acrylic acid with molecular oxygen proceeds in two consecutive along the reaction coordinates stages, the first of which leads to acrolein and the second one to acrylic acid.

This reaction in two consecutive feet enables stage In the method according to the invention in two adjacent zones, and in each of the two oxidation zones is subject to enforcement oxide catalyst can be optimally adjusted. For the first oxidation zone (propylene→acrolein), as a rule, it is preferable to apply the catalyst on the basis of containing a combination of elements Mo-Bi-Fe oxide of the metals, while for the second oxidation zone (acrolein→acrylic acid) usually preferred catalysts on the basis of containing a combination of elements Mo-V oxides of metals.

Appropriate catalysts based on metal oxides for both oxidation zones many times already described in literature and known to the person skilled in the art. For example, in the publication EP-A 253409 on page 5 provides a reference to related U.S. patents.

Suitable catalysts for both oxidation zones are described in DE-A 4431957 and DE-A 4431949, especially the catalysts of the General form I of these two publications. the AK rule, a mixture of the product from the first oxidation zone is transferred to the second oxidation zone without intermediate processing.

The simplest form of implementation of both oxidizing zones in a tubular reactor in which the catalyst loading appropriately changes along individual contact tubes at the end of the first stage reaction (such suitable according to the invention as a stage In the partial oxidation of propylene is described, for example, in EP-A 911313, EP-A 979813, EP-A 990636 and DE-A 2830765). If necessary, download the contact tubes catalyst is interrupted by backfilling with an inert material.

Preferably both the oxidation zone are implemented in the form of two connected in series systems pipe sections. They can be present in the reactor, and the transition from one section of pipe to another pipe sections are formed are not placed in contact with the pipe the filling of inert material. While the contact tube, as a rule, are streamed cooled, it reaches placed, as described above, backfill with inert material. Therefore, both sections of the contact tubes placed in spatially separated from each other reactors. As a rule, between the two sectional reactors is an intermediate cooler to decrease occurred additional combustion acrolein in the gas mixture leaving the first with open oxidation. Instead sectional reactors may apply heat exchanger plate reactors with salt by cooling and/or cooling by evaporation, for example described in DE-A 19929487 and DE-A 19952964.

The reaction temperature in the first oxidation zone is generally from 300°With up to 450°C, preferably from 320°With up to 390°C. the reaction Temperature in the second oxidation zone is generally from 200°to 300°often from 220°C to 290°C. the Reaction pressure in both zones of oxidation ranges from 0.5 to 5, preferably from 1 to 3 ATM. Load (N/l·h) oxidation catalysts, the reaction gas is for both zones of oxidation of from 1500 to 2500 h^-1accordingly, up to 4000 h^-1.

Both oxidation zone in the method according to the invention can be performed as described in DE-A 19837517, DE-A 19910506, DE-A 19910508, also DE-AND 19837519. Usually the temperature in both zones of oxidation, if necessary, in the multi-zone reactor system adapted to the special composition of the gaseous reaction mixture, and the catalyst loading.

Required for required according to the invention stage as a means of oxidation with molecular oxygen to pre-add to his total gas mixture phase C. However, oxygen can be added after the first oxidation zone.

Preferably in the first the first oxidation zone to set the molar ratio of propylene and molecular oxygen is from 1:1 to 3, often from 1:1.5 to 2. The same numeric value suitable for the molar ratio of acrolein and molecular oxygen in the second zone of oxidation.

In both the zones of oxidation of an excess of molecular oxygen, generally provides the advantage with respect to the kinetics of gas-phase oxidation. In contrast to conditions on stage And method according to the invention on thermodynamic relationships generally not influenced by the molar ratio of the reagents, as heterogeneous catalyzed gas-phase partial oxidation of propylene to acrylic acid is subjected to kinetic control. Therefore, in principle, for example, in the first zone of oxidation of propylene can be in molar excess with respect to molecular oxygen. In this case, the excess propylene actually plays the role of the diluent gas.

In principle, heterogeneous catalyzed gas-phase partial oxidation of propylene to acrylic acid can be carried out in one zone of oxidation. In this case, both stages of oxidation occurs in one oxidation reactor loaded with catalyst which catalyzes both steps of the reaction. Needless to say, the catalyst loading can also be changed within the oxidation zone along the reaction coordinate smoothly or discontinuously. When the form of execution used in the invention stage, with d uma consistently enabled zones of oxidation of leaving the first zone of oxidation of the gas mixture can be separated completely or partially contained therein, incurred in the first zone of oxidation as by-products carbon dioxide and water vapor before entering the second zone of oxidation. Preferably choose such a form of execution in which such separation is not required.

The source is required at the stage of oxidation To molecular oxygen which mixes with the gas mixture a' before applying it to load stage oxidation, suitable as a pure molecular oxygen or diluted with an inert gas, such as CO₂, CO, noble gases, N₂and/or saturated hydrocarbons with molecular oxygen.

An expedient manner for at least partial coverage needs molecular oxygen as the oxygen source may be used air, as thus applied at the stage In the molecular oxygen may be introduced into the reaction system.

The gas mixture A' is preferably only of propane and propylene (the share of the different components is at this ≤5 vol.%, consequently, ≤2 vol.%), and as the source of molecular oxygen, at a subsequent stage In can be used only air.

The addition of cold air to the hot gas mixture a' in the framework of the method according to the invention can be directly cooled gas mixture a'.

the case if acrolein is the target product, at the stage In the second oxidation zone is no longer used.

Leaving the stage In the invention of the gas mixture, as a rule, consists mainly of the target product acrolein, or acrylic acid, or mixtures thereof, not into molecular oxygen, propane, molecular nitrogen, which emerged as a by-product and/or applied as a gas diluent water vapor as a by-product and/or gas-solvent carbon monoxide, and small amounts of other lower aldehydes, hydrocarbons and other inert gaseous diluents.

The target product can be separated from the gas mixture In known per se manner (e.g., partial condensation of acrylic acid, or by absorption of acrylic acid in water or in high-boiling hydrophobic organic solvent, or by absorption of acrolein in water or in aqueous solutions of lower carboxylic acids, as well as subsequent processing of absorbents). Alternative gas mixture can fraktsionirovannoe condensing (see, for example, the publication EP-A 117146, DE-A 4308087, DE-AND 4335172, DE-A 4436243, DE-A 19924532, and also DE-A 19924533).

Not converted acrolein and/or propylene N, if necessary, also be separated and returned to the stage Century.

However other than acrylic acid and acrolein significant the s components remaining after the separation of the target product gas depending on the needs and applied dehydrogenation catalyst can be separated and/or return with propane as the circulation gas to the stage dehydrogenation And to influence the conversion of the dehydrogenation as described above. However, it is not converted propane may also be returned in a mixture with not converted propylene at stage A. If the continuous carrying out of the method according to the invention therefore there is a continuous conversion of propane to acrylic acid and/or acrolein.

The separation of propane and propene from remaining after the separation of the target product of the residual gas it contains, as a rule, About₂, CO, CO₂N₂Oh, N₂noble gases and other lower aldehydes and hydrocarbons) may, as described above, be performed by absorption with subsequent desorption and/or Stripping (and re-absorbers) in the high-boiling hydrophobic organic solvent. Further features of the Department are adsorption, rectification and partial condensation.

When applying the dehydrogenation catalysts which are sensitive to oxygen or oxygen-containing compounds, these oxygenates before returning from the circulating gas phase And is separated from the circulating gas. This separation of oxygen may make sense also to prevent oxidation of propane on stage And dehydrogenation. The dehydrogenation catalysts known from DE-A 19937107, not susceptible to oxygenates (cha is in the surrounding area, in examples 1 to 4 of this publication).

Another feature of the Department is fractionated distillation. Preferably fractionated distillation under pressure is carried out at low temperatures. The applied pressure may be, for example, from 10 to 100 bar. As distillation columns can be used in Packed columns, plate columns or columns with the rebuilding. As plate columns suitable columns with double-flow plates, cap plates or valve plates. Reflux can be, for example, from 1 to 10. Other departments are, for example, extraction under pressure, absorption with changing pressure, flushing under pressure, partial condensation and extraction under pressure.

Needless to say, according to the invention the total amount of residual gas may return to the stage A. In this case, the issue other than propane, propene, molecular oxygen gas components can be exclusively between the mixture and the mixture A'.

Needless to say, there may be another release after the separation of the target product. In that case, if returned to the dehydrogenation of propane recycle gas contains carbon monoxide, he may, before he complemented the fresh propane, catalitic the sky burned with obtaining CO ₂. Released during the heat of reaction can be used for heating the mixture at a temperature of dehydrogenation.

Catalytic combustion is contained in the residual gas FROM obtaining CO₂may also be recommended when the separation of carbon monoxide from the residual gas is carried out before his return as a recirculating gas to propane dehydrogenation, however, relatively easy to separate the CO₂(for example, a main washing liquid).

Of course, there is the possibility of returning part of the residual gas without a change to the dehydrogenation of propane and only remaining part to separate propane and propene in the mixture and also to return to the propane dehydrogenation and/or on stage Century. an Expedient manner in the latter case, the remaining part of the residual gas combine with a gas mixture of A.

In the framework of the fractionated distillation of the residual gas separation can be performed so that the head part of rectification columns are separated in substantially all components boiling point which is lower than the boiling point of propene. These components are primarily of carbon monoxide CO and CO₂and not converted oxygen and ethylene, and methane and N₂.

Often the method according to the invention is carried out in such a way that the gas is Messi turned In at least 70 mol.%, preferably 80 mol.% General summarized at various levels of molecular oxygen.

Preferably in the method according to the invention in the second zone of the oxidation stage In the work when the molar ratio of acrolein : molecular oxygen : water vapor : propane : molecular nitrogen, and other gases as diluents, equal to from 1:0.5 to 1:0.1 and 1:0.5, and up to 6:1 to 10:0 to 5.

The advantage achieved by the invention reduced education propion-aldehyde and/or propionic acid as by-products takes place mainly regardless of catalysts based on metal oxides are applied at the stage In the invention. The advantage is also regardless of whether the volume-specific activity of the catalyst at the stage of constant or increases along the reaction coordinate.

In particular, the advantage according to the invention when in the first zone of the oxidation stage In the used catalysts based on metal oxides which correspond to the General formula I or I' or II from the publication DE-a 19910508.

As the geometry of the catalysts according to the invention is suitable for the first and second zones of oxidation on the stage according to the invention such as described in the publication DE-A 19910506, respectively, DE-A 19910508.

Further recommended to the stage In a tubular sectional is ectory, with regard to the flow direction of the reaction gas and the environment temperature (for example, a salt bath), can be operated in the mode of direct flow or counterflow. Transverse threads may also be overlapped. Particularly beneficial leandrohavana the direction of the flow temperature around the contact tube, which may be carried out in one direction or in countercurrent to the reaction gas mixture.

Typically, stage And according to the invention are used reactors with passivated internal walls. Passivation can occur, for example, due to the fact that on the inner wall before dehydration is applied agglomerated alumina.

Passivation may be also carried out in situ by means of additives to the reaction gas mixture a small amount of passivating of auxiliary substances (e.g., sulfides).

According to the invention can also be a way so that in the time that is regenerative catalyst loading for the dehydrogenation of propane, installation of acrylic acid is supplied with propene from another source (e.g., cracking, piping, and tanks). In this case, no additional dehydrogenation reactor for regeneration phase.

In conclusion, it should be noted that the way in which obreteniyu also includes such methods, in which at least a part formed on the stage And hydrogen, integrated on the stage And quasi in situ continuously removed (e.g., burned), for example, by oxidation to water vapor by means of additionally added to the catalyst in the dehydrogenation of recoverable metal oxide, as described in the publication EP-A 832056.

Examples

A) obtaining a catalyst based on metal oxides for the oxidation stage

1. Getting the initial mass 1

In 775 kg BW of an aqueous nitric acid solution of bismuth nitrate in (11.2 wt.% Bi, free of nitric acid of from 3 to 5 wt.%; mass density of 1.22 to 1.27 g/ml) was injected at 25°With portions 209,3 kg of tungstic acid (72,94 wt.% W). Rezultiruyushchuyu water mixture is then stirred for another 2 hours at 25°and then spray dried.

Spray drying is carried out in a rotary-disk spray column in the input gas temperature of 300±10°and when the output temperature of the gas in 100±10°C. the resulting powder was calicivirus at a temperature in the range from 780 to 810° (propulsively air rotary tube furnace (1.54 m³an internal capacity of 200 nm³air/h)). Essential to accurately set the temperature of calcination is that it should be made with focus on the desired phase composition of the products is the calcination. Desirable are phase WO₃(monocline) and Bi₂W₂O₉, is the presence of unwanted γ-Bi₂WO₆(russellite). If, after calcination connection γ-Bi₂WO₆still it is possible to determine on the basis of the reflex x-ray diffraction pattern at an angle of reflection 2 single. = 28,4° (CuKα-radiation), you should repeat the process and increase the temperature of calcination within the specified range, is not yet achieved the disappearance of the reflex. Thus obtained calcined mixed oxide is crushed, so that the value of X₅₀(see publication Ullmann''s Encyclopedia of Industrial Chemistry, 6^thEdition (1998) Electronic Release, Kapitel 3.1.4 or DIN 66141) rezultirase grain size is 5 mm, the Crushed material is mixed with 1 wt.% (in terms of the crushed material) thin SiO₂(vibrac. weight 150 g/l; the value of X₅₀particles of SiO₂is 10 mm, a BET surface of 100 m²/g).

2. Obtaining initial mass of 2

The solution And get so that at 60°with stirring, dissolved in 600 l of water 213 kg heptamolybdate aluminum and the resulting solution while maintaining the temperature 60°and with stirring, mixed with 0,97 kg having a temperature of 20°With an aqueous solution of potassium hydroxide (46,8 wt.% KON).

The solution is To get so that at 60°With the 262,9 kg of an aqueous solution of cobalt nitrate (12.4 wt.% ) Enter 116,25 kg of an aqueous solution of iron nitrate (14.2 wt.% Fe). After that, while maintaining the temperature 60°With the solution continuously shaking for 30 minutes in solution A. Then, the reaction mixture is stirred for 15 minutes. Then to rezultirase aqueous reaction mixture are added 19,16 kg of silica gel (46,80 wt.% SiO₂a density of from about 1.36 to 1.42 g/ml, pH from 8.5 to 9.5, alkali content Max. of 0.5 wt.%) and then within 15 minutes, stirred at 60°C.

In conclusion, spray dried in a rotary-disk spray column in countercurrent flow (inlet gas temperature of 400±10°C, the temperature of the gas output 140±5°). The resulting powder has a loss on ignition of about 30 wt.% (calcination for 3 hours at 600°).

3. Getting active mass of metal oxides and catalyst

The initial weight of 1 is homogeneous mixed with the original mass of 2 required for active mass of the metal oxide stoichiometry

[Bi₁₂W₂O₉·2WO₃]_0,5[Mo₁₂Co_5,5Fe_2,94Si_1,59K_0,08O_x]₁

In terms of the total weight admixed additionally homogeneity of 1.5 wt.% thin graphite (sieve analysis: min 50 wt.% <24 µm, Max. 10 wt.% >24 μm and <48 μm, maximum 5 wt.% >48 μm, the surface on BET: 6 to 13 m²/g). The obtained dry mixture pressed into hollow cylinders with a length of 3 mm, an external diameter of 5 mm and wall thickness 1,5mm, and then thermally treated as follows.

In propulsively air muffle furnace (60 liters internal volume of 1 nl/h of air per gram of precursor of active mass) is heated at 180°S/h first from room temperature (25° (C) to 190°C. This temperature was kept for 1 hour and then at 60°/h heated to 210°C. a Temperature of 210°also withstand for 1 hour before it increases with speed 60°/h to 230°C. This temperature is again incubated for 1 hour, then heated at 60°C/h up to 265°C. Next, the temperature of 265°C is maintained during 1 hour. After that the reaction mixture is first cooled to room temperature and it mostly to finish phase decomposition. Then with a heating rate of 180°/h the reaction mixture is heated to 465°and the temperature of calcination was incubated for 4 hours. This rezultirase suitable for the first oxidation zone stage catalyst In ring V.

C) obtaining a catalyst based on metal oxides for the second oxidation zone stage

1. Getting a catalytically active oxide mass Mo₁₂V₃W_1,2Cu_2,4About_n

190 g of copper (II) acetamidate dissolved in 2700 g of obtaining solution I. In 5500 g of water at a temperature of 95°With successively dissolved 860 heptamolybdate is agitate ammonium, 143 g metavanadate ammonium and 126 g paraformadehyde ammonium obtaining solution II. After this, the solution I for once mixed with solution II and then add as many 25 wt.%-aqueous NH₃solution that again there is a solution. This solution is subjected to spray-dried at an outlet temperature of 110°C. the resulting powder was plastificator with 0.25 kg of 30 wt.%-aqueous solution of acetic acid per 1 kg of the powder in the plasticizer of the firm Werner &Pfleiderer type ZS1-80 and then at a temperature of 110°dried for 10 hours in an oven.

700 g of the obtained pre-catalyst calicivirus in a mixture of air and nitrogen [(200 nl N₂/15 nl air)/h] in a rotary tube furnace (length 50 cm, with an inner diameter of 12 cm). In the framework of the calcination plastificator mass is first heated for 1 hour at room temperature (about 25° (C) to 325°C. After 4 hours of aging at this temperature. Then within 15 minutes, the mass is heated to 400°C, kept at this temperature for 1 hour and then cooled to room temperature.

Calcined catalytically active material is ground into fine powder, from which 50% of the powder particles pass through a sieve with openings of 1 to 10 mm and the proportion of particles with a longitudinal size of either the 50 mm which is less than 1%.

2. Getting a shell catalyst

28 kg annular carrier (7 mm external diameter, 3 mm length, 4 m inner diameter, steatite, with a surface roughness Rz according to the publication EP-714700 45 mm and with a total volume of pores ≤1 vol.%, in terms of the volume of the carrier, the manufacturer firm: Ceramtec DE) fill in the drageeing boiler (angle of inclination 90°; type Hicoater company Lödige, DE) with a capacity of 200 HP then the drageeing boiler is put into rotation with 16 rpm Through the nozzle for 25 minutes napraschivaet 2000 consisting of 75 wt.% H₂O and 25 wt.% glycerin aqueous solution. At the same time in the same period of time continuously add 7,35 kg catalytically active oxide powder from stage a) with a vibrating tray outside raspryskivateli cone resprectively nozzles. During the coating summed powder is completely absorbed by the surface of the carrier, is not observed agglomeration thin oxide active mass. After the additive powder and aqueous solution at a speed of 2 rpm at 110°C for 20 minutes in the drageeing boiler is blown into the hot air. Then for 2 hours at 250°resting in the backfill (shelf oven) dried under air. Get the annular suitable for the second oxidation zone stage In shell catalysts S, the proportion of the oxide of the act the main mass in terms of the total weight is 21 wt.%. The thickness of the shell, if you look at the surface of one carrier, and also on the surface of a variety of media is 240±25 mm

C) Loading suitable for the stage In the pipe reactor system R and its temperature control

1. Download first reaction tubes

The reaction tube (steel type V2A; external diameter 30 mm, wall thickness 2 mm, internal diameter 26 mm, length 439 cm and centered in the middle of the reaction tube termitrab (6 mm external diameter) for receiving thermocouple, which allows you to measure the temperature in the reaction tube) load from the bottom up on the contact element (32 cm) first length 30 cm with a rough surface of steatite beads (diameter 4 to 5 mm; inert material to heat output of the reaction mixture), then spend a load of 100 cm, which consists of a homogeneous mixture of 373 g of the catalyst rings V of A), and 160 g of steatite rings of geometry 5 mm × 3 mm × 2 mm (external diameter × length × wall thickness). Download reaction tubes complete backfilling length of 170 cm from the catalyst rings V of a) and then filling in length 107 cm from the already mentioned, having a rough surface staticobj beads (diameter 4 to 5 mm).

2. Download the second reaction pipe

The reaction pipe (type steel V2A, with external diameter is trom 30 mm, with wall thickness 2 mm, internal diameter 26 mm, length 441 cm, and also with centered on the middle of the reaction tube thermotropic (external diameter 6 mm) to accept thermocouple, which allows you to determine the temperature in the reaction tube) load from the bottom up on the contact element (length 34 cm) first, length 200 cm shell catalyst S) and then along the length of 100 cm shell catalyst S' (made the same way as shell catalyst S, the proportion of the oxide active material calculated on the total weight of only selected on 17 wt.%). Download a length of 56 cm having the rough surface of steatite beads (diameter 4 to 5 mm) finishes loading the reaction tubes.

3. The connecting pipe

The first and second reaction pipes at their opposite contact element ends are connected to each other by the connecting pipe (type steel V2A, length 1 m, inner diameter 9 mm). The pipe is in the middle to complement containing molecular oxygen gas.

4. The temperature control system of the reaction tubes

For the temperature control of the reaction tubes used inflated salt melt. Inflated the salt melt to the first reaction tube is maintained at a temperature of X°S. Pumped molten salt for the second reaction tube myderived is at a temperature of Y° C. the pipe is maintained at a temperature of 200°With (by means of electric heating elements).

D) Carrying out gas-phase oxidation

1. The composition of the reaction gas mixture As:

2. The composition of the reaction gas mixture:

3. The composition of the reaction gas mixture:

The system of the reaction tubes from stage C) is loaded, the reaction gas mixture And, accordingly, the reaction gas mixture, respectively, of the reaction gas mixture C. the Supply of the reaction gas mixture is carried out in the first reaction tube, and it is available on the contact element end of the tube.

Load the catalyst loading of the first reaction tube is chosen so that it is 100 nl of propene/l catch (h^-1). In a fitting for all three cases it is supplemented with 75 nl/h with a room temperature of molecular oxygen

The temperature control system of the reaction tubes is chosen so that in all three cases in terms of a single passage is provided in the first reaction tube, the conversion of propene to 94 mol.% and in the second reaction pipe conversion formed in the first reaction pipe acrolein in 97.5 mol.%.

After operating for 10 hours leaving the second reaction tube, the reaction gas mixture is analyzed for the content of propionic acid (calculated on the total content of acrylic acid).

The following table reflects the results.

1. The reaction gas mixture And

X=328°

Y=270°C

The content of propionic acid: 0,02 mol.%.

2. The reaction gas mixture In

X=358°

Y=295°

The content of propionic acid: to 0.14 mol.%.

3. The reaction gas mixture With

X=343°

Y=281°C

The content of propionic acid: 0,08 mol.%.

The formation of propionic acid as a side product in the event more than six times higher than in case A, which suggests that the use of the Molek is Yarnykh nitrogen as the diluent gas reduces the formation of propionic acid as a by-product.

(E) Catalytic combustion with the formation of CO₂in the gas mixture), which is already separated target products.

The gas mixture of 2.5% vol. CO, 1% vol. of propene, 82% vol. propane and 14.5% vol. a mixture of H₂O, N₂and CO₂at a temperature of 212°With (temperature control carried out by using superimposed on the reaction tube aluminum block, which is temperature-controlled electric heating elements) after the additive terms WITH double the stoichiometric amount of molecular oxygen is passed through the fixed layer (inner diameter 20.5 mm, the tube is centered with an external diameter of 4 mm thermogels for internal thermocouple, length backfill 19 cm) commercially available catalyst BASF on noble metals RO 20 (round pellets with a diameter of 3 mm, Al₂About₃as a carrier, Pd as the active component of the noble metal) (when the load of the catalyst gas mixture in 1680 h^-1). From contained in the gas mixture WITH 94 mol.% burn with the formation of CO₂. Other components remain largely unchanged. Subsequent separation of propane and propene from a gas mixture conducted fractionated distillation.

Examples

I.

Repeated experience D) for carrying out the gas-phase oxidation, and used the reaction gas mixture, free is from water vapor, i.e. in the composition of these mixtures as additional the diluent gas includes nitrogen (*), propane (*) or a mixture of nitrogen and propane (*):

1. The composition of the reaction gas mixture a*:

2. The composition of the reaction gas mixture In*:

3. The composition of the reaction gas mixture With*:

This got the following results:

1. The reaction gas mixture A*

X=334°

Y=275°

The content of propionic acid: 0.02 mol.%.

2. The reaction gas mixture In*

X=363°

Y=300°

The content of propionic acid: 0.17 mol.%.

3. The reaction gas mixture With*

X=348°

Y=286°

The content of propionic acid: 0.09 mol.%.

The above data indicate that the same is aemy technical result i.e. a significant decrease in the formation of undesirable by-products, namely Propionaldehyde and/or propionic acid, at a stage oxidation of propylene, is also achieved in the absence of water vapor as a gas-Sortavala. While these data clearly confirm the fact that the essential is only the presence in the reaction mixture of nitrogen as an additional gas diluent.

II.

Repeated experience D) for carrying out the gas-phase oxidation with low water content (5% vol. instead of 10 vol.%):

1. The composition of the reaction gas mixture a**:

2. The composition of the reaction gas mixture A**:

3. The composition of the reaction gas mixture With**:

This got the following results:

1. The reaction gas mixture A**

X=329°

Y=to 271.5°C

The content of propionic acid: 0.02 mol.%.

2. The reaction gas mixture In**

X=360°

Y=297°

The content of propionic acid: 0.15 mol.%.

3. The reaction gas mixture With**

X=344,5°

Y=283°

The content of propionic acid: 0.08 mol.%.

The above data indicate that the contents in the reaction mixture of water vapor has virtually no effect on the achievement of the technical result.

III.

Conducted partial heterogeneous catalytic dehydrogenation according to stage a) of claim 1 of the claims.

The reaction was carried out in a tubular reactor is known from DE 10219879 the dehydrogenation catalyst on the carrier ZrO₂/SiO₂formula Pt_{for 0.3}Sn_{for 0.6}La_3,0Cs_0,5K_{of 0.2}(ZrO₂)_88,3(SiO₂)_7,1at a temperature of 590°C. Used original gas mixture of the following composition:

This conversion of propane in both experiments was 19.8 mol.%, and selectivity - 91 mol.%.

1. The method of producing acrolein or acrylic acid or mixtures thereof, in which

A) in the first stage And the propane is subjected to partial heterogeneous catalyzed dehydration in the gas phase with the formation of the gas mixture And the product containing molecular hydrogen, propylene, not converted propane and other than propane and propene components

C) contained in the gas mixture And the product stage And other than propane and propylene components produce at least a partial quantity of molecular hydrogen and the mixture obtained after this selection is used as the gas mixture a', the second stage In to boot, at least one oxidation reactor in at least one reactor for the oxidation of propylene is subjected to selective heterogeneous catalyzed gas-phase partial oxidation with molecular oxygen to obtain the target product gas mixture containing acrolein or acrylic acid or mixtures thereof, the

(C) from received within the partial oxidation of propylene on stage In the gas mixture In the third stage With separate acrolein or acrylic acid or mixtures thereof as the target product and at least contained in the gas mixture phase In not converted propane return to the stage dehydrogenation And,

characterized in that in the framework of partial oxidation of propylene on stage In applied molecular nitrogen as an additional gas diluent.

2. The method according to claim 1, characterized in that stage a) and/or (C) is carried out in the presence of water vapor.

3. The method according to claim 1 or 2, characterized in that allocated to stage C), at least a partial quantity of molecular hydrogen returns to the step (A).

4. The method according to one of claims 1 to 3, characterized in that the boot gas mixture, at least one of the rector of the oxidation in the second stage contains, in terms of the contained propylene, at least 5 mol.% molecular nitrogen.

5. The method according to one of claims 1 to 3, characterized in that the boot gas mixture, at least one oxidation reactor in the second stage contains, in terms of the contained propylene, at least 50 mol.% molecular nitrogen.

6. The method according to one of claims 1 to 3, characterized in that the boot gas mixture, at least, real the oxidation reactor to the second stage contains, in terms of contained propylene, at least 100 mol.% molecular nitrogen.

7. The method according to one of claims 1 to 6, characterized in that the molar ratio contained in the boot of the gas mixture, at least one oxidation reactor of the second stage In a number of molecular nitrogen contained in the same boot gas mixture the quantity of propane is at least 0,05.

8. The method according to one of claims 1 to 6, characterized in that the molar ratio contained in the boot of the gas mixture, at least one oxidation reactor of the second stage In a number of molecular nitrogen contained in the same boot gas mixture the quantity of propane is at least from 0.05 to 5.

9. The method according to one of claims 1 to 6, characterized in that the molar ratio contained in the boot of the gas mixture, at least one oxidation reactor of the second stage In a number of molecular nitrogen contained in the same boot gas mixture the quantity of propane is at least 0.5 to 3.

10. The method according to claim 1, characterized in that the composition of the boot of the gas mixture, at least one oxidation reactor in the second stage performs the following molar ratio:

propane:propene:N₂:O₂:H₂A:other connections

= 0.5 to 20:1:0.1 to 40:0.1 to 10:0 to 20:0 to 1.

11. The method according to claim 1, characterized in that the composition of the boot of the gas mixture, at least one oxidation reactor in the second stage performs the following molar ratio:

propane:propene:N₂:O₂:H₂A:other connections

= 2 to 10:1:0.5 to 20:0.5 to 5:0.01 to 10:0 to 1.

12. The method according to claim 1, characterized in that the composition of the boot of the gas mixture, at least one oxidation reactor in the second stage performs the following molar ratio:

propane:propene:N₂:O₂:H₂A:other connections

= 3 to 6:1:1 to 10:1 to 3:0.1 to 2:0 to 0.5.

13. The method according to one of claims 1 to 12, characterized in that the molar ratio contained in the gas mixture And propylene contained in the gas mixture And the molecular hydrogen is ≤100.

14. The method according to one of claims 1 to 12, characterized in that the molar ratio contained in the gas mixture And propylene contained in the gas mixture And the molecular hydrogen is ≤50.

15. The method according to one of claims 1 to 12, characterized in that the molar ratio contained in the gas mixture And propylene contained in the gas mixture And the molecular hydrogen is ≤10.

16. The method according to one of claims 1 to 15, characterized in that the molar ratio contained in the gas mixture And propylene contained in the gas is Oh mixtures And molecular hydrogen is ≥ 0,05.

17. The method according to one of claims 1 to 16, characterized in that the stage And the conversion of propane, in terms of single pass, is from 5 to 25 mol.%.

18. The method according to one of claims 1 to 16, characterized in that it is obtained at the stage And the conversion of propane, in terms of single pass, is from 10 to 20 mol.%.

19. The method according to 17 or 18, characterized in that subject to dehydrogenation of propane on stage And dilute with water vapor.

20. The method according to claim 19, characterized in that the molar ratio of water vapor to be the dehydrogenation of propane is from 0.1 to 2.

21. The method according to 17 or 18, characterized in that the variable dehydrogenation of propane added molecular hydrogen.

22. The method according to item 21, wherein the molar ratio of molecular hydrogen to be the dehydrogenation of propane is >0 and ≤5.

23. The method according to one of PP-22, characterized in that the partial, heterogeneous catalyzed dehydrogenation of propane performed on stage And o adiabatically.

24. The method according to one of PP-23, characterized in that the partial, heterogeneous catalyzed dehydrogenation of propane performed on stage And in the reactor with a fixed bed with axial or radial flow.

25. The method according to one of PP-23, characterized in that the partial heterogeneous catalyzed degidrirovanie the propane on stage And performed in lattice reactor.

26. The method according A.25, characterized in that the temperature of the reaction gas mixture in the whole lattice reactor ranges from 450 to 550°C.

27. The method according to p. 25 or 26, characterized in that the lattice reactor contains spatial successive from 2 to 8 catalyst layers.

28. The method according to one of PP-27, characterized in that the reaction gas mixture during partial, heterogeneous catalyzed dehydrogenation add molecular oxygen.

29. The method according to one of claims 1 to 28, characterized in that the gas mixture And before its use as a gas mixture a' separate the contained amount of molecular hydrogen.

30. The method according to one of claims 1 to 28, characterized in that the gas mixture And before its use as a gas mixture a' is separated other than propane and propylene components.

31. The method according to one of claims 1 to 28, characterized in that the gas mixture And other than propane and propylene components are separated so that the gas mixture And put in contact with an organic solvent, it selectively adsorb propane and propylene, followed by desorption them again release and as the gas mixture a' is used to load, at least one oxidation reactor in stage C.

32. The method according to one of claims 1 to 31, characterized in that to download the key, at least one oxidation reactor stage used In the air.

33. The method according to one of claims 1 to 32, characterized in that the gas mixture In separate contained acrolein and/or acrylic acid and from remaining when this residual gas, at least a partial amount of return to the stage dehydrogenation A.

34. The method according to item 30, wherein the gas mixture is separated therein acrolein and/or acrylic acid and the total amount remaining when this residual gas return to the stage dehydrogenation A.

35. The method according to one of claims 1 to 32, characterized in that the gas mixture In a first separate the contained acrolein and/or acrylic acid from remaining when this residual gas is separated other than propane and propylene components and the remaining propane and propylene return to the stage dehydrogenation A.

36. The method according to one of claims 1 to 35, characterized in that stage b consists of two cascaded sectional tubular reactors.

37. The method according A.25, characterized in that the lattice reactor contains at least one catalyst layer, which catalyzes the combustion of hydrogen.

38. The method according to claim 1, characterized in that it is done as a way of obtaining acrolein.

39. The method according to claim 1, characterized in that it is done as a way the floor is placed acrylic acid.