Method for preparing acrolein and/or acrylic acid

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for synthesis of acrolein and/or acrylic acid from propane and/or propene. Method involves the following steps: (a) isolating propane and/or propene from gaseous mixture A containing propane and/or propene by their absorption with adsorbent; (b) isolating propane and/or propene from adsorbent to form gas B containing propane and/or propene, and (c) using gas B obtained in stage (b) for oxidation of propane and/or propene to acrolein and/or acrylic acid wherein the heterogeneous catalytic dehydrogenation of propane without feeding oxygen is not carried out. Method shows economy and maximal exploitation period of used catalyst without its regeneration.

EFFECT: improved method of synthesis.

12 cl, 7 dwg, 1 ex

The present invention concerns a method of producing acrolein and/or acrylic acid from propane and/or propene.

Acrolein and acrylic acid are important chemical products. Thus, acrylic acid is used, in particular, as a starting monomer for polymers, aqueous dispersions which are used, for example, as a binder. Depending on the scope of application of these polymers of acrylic acid before polymerization can be subjected to esterification. Acrolein is an important intermediate used, for example, to obtain glutaraldehyde, methionine, Polevoy and acrylic acid.

According to the known methods initial products to obtain acrolein and/or acrylic acid are propane and/or propene. From German patent application DE-A 3313573 and European patent application EP-A-0117146 known two - or three-stage method for the conversion of propane to acrolein and/or acrylic acid, in the first stage, which carry out the dehydrogenation of propane to propene, and in the second phase oxidation of propene to acrolein. An important feature of this method is that propane is not separated between the first and second stages from which is formed with its dehydrogenation side components, such as molecular hydrogen. Oxidation of propene carry out the terms excluding significant oxidation of hydrogen. At the third stage of acrolein may be subjected to oxidation to acrylic acid. In addition, the possibility of selection neprivrednih on the second or third stage of propane and propene by their absorption and return to the first stage (stage dehydrogenation) after separation from the absorbent.

In Japanese patent application JP-A-10-36311 describes how to obtain α,βunsaturated carboxylic acids, in particular acrylic acid by gas-phase oxidation of propane in the presence of a composite catalyst based on a metal oxide, and to achieve a high yield of the target product ratio of propane to oxygen and, optionally, gaseous diluent in the composition of the initial mixture is supported within a certain range, while ensuring a certain degree of conversion of propane. Neprevyshenie propane can be separated from the reaction products using selective separator, comprising a device for adsorption at a variable pressure-Swing Adsorption), and again subjected to gas-phase oxidation.

In the patent application great Britain GB 1378178 described method, according to which neprevyshenie during the oxidation of hydrocarbons absorbed by the absorbent is subjected to further Stripping, using the appropriate marivaudage means, which add to the non-allocation of the hydrocarbon in an amount such that the composition of the mixture was outside the ignition.

The present invention was to provide a method of gas-phase catalytic get acrolein and/or acrylic acid from propane and/or propene, characterized by efficiency and maximum possible duration of operation of the used catalyst without regeneration.

According to the invention this problem is solved by absorption of the absorbent propane and/or propene from containing these hydrocarbons mixture, separation of the propane and/or propene from the absorbent and the use of propane and/or propene for subsequent oxidation to acrolein and/or acrylic acid.

Thus, the invention concerns a method of producing acrolein and/or acrylic acid from propane and/or propene, comprising the following stages:

a) selection of propane and/or propene from the containing propane and/or propene gas mixture And by their absorption by the absorbent,

b) selection of propane and/or propene from the absorbent with a receipt containing propane and/or propene gas and

(c) obtained in stage (b) gas for oxidation of propane and/or propene to acrolein and/or acrylic acid,

and between stages (b) and (C) does not produce the heterogeneous catalytic degidrirovanie the propane without oxygen. Preferred embodiments of the invention are given in the following description and associated drawings.

Because propane and/or propene before stage oxidation allocate absorption, the gas typically contains residual amounts of the adsorbent. It was unexpectedly found that in spite of this oxidation proceeds without any difficulty. In particular, it was not observed any significant reduction in the activity of the oxidation catalyst, which can be operated for a long period without regeneration. In addition, there have been no problems caused, if necessary, taking place on the stage of oxidation of propane and/or propene formation of any oxidation products of the absorbent. If the presence of residual absorbent and creates certain difficulties, which were usually absent, if the absorbents use of high boiling point hydrocarbons, the absorbent material may be removed, for example by water quenching or adsorption.

According to the German patent application DE-A 3313573 recovered (highlighted) by the absorption of propane and propene return to the stage heterogeneous catalytic dehydrogenation of propane, in the exercise of which may occur decontamination appropriate catalyst, for example, result is the coking, therefore the dehydrogenation catalysts require frequent regeneration. The presence of absorbent material sent to the dehydration of the gas stream does not create any problems, since the absorbent capable of burning together with products of coking. The catalysts used for the oxidation of propene to acrolein and/or acrylic acid, usually do not regenerate as often, so the additional cost of regeneration due to the presence in the used gas absorbent, there are more significant than dehydration. The advantage of the method according to the invention is that the oxidation catalyst over a long period of time can be used without regeneration.

The method according to the invention differs from the method according to the German patent application DE-A 3313573 that selected by the absorption of propane and/or propene is directed to a stage of oxidation. Another difference method according to the invention is that between the stages of selection of propane and/or propene from the absorbent and their oxidation to acrolein and/or acrylic acid do not produce heterogeneous catalytic dehydrogenation of propane without oxygen.

In the framework of the present invention under the gas may also be implied gas mixture.

At stage (a) can be used gas mixture And with any content of propane and/and the and propene. The preferred molar ratio of propane and propene in the gas mixture And ranges from 0:100 to 100:0, in particular from 10:90 to 90:10, often from 80:20 to 40:60.

Gas mixture And preferably contains at least one additional, different from propane and/or propene component type which is not subject to any special limitations and, as a rule, is determined by the origin of the gas mixture. In particular, we are talking of at least one component selected from the group comprising oxygen, hydrogen, oxides of carbon, in particular monoxide or carbon dioxide, side components formed during the dehydrogenation of propane, gas-phase oxidation of propene to acrolein and/or acrylic acid or oxidation of propane to acrolein and/or acrylic acid. An additional component is often at least hydrogen, oxygen, carbon monoxide or a mixture of these gases.

As used in stage (a) absorbents in principle any suitable, able to absorb propane and/or propene absorbents. Under the absorbent imply preferably an organic solvent, which preferably is hydrophobic and/or high-boiling compound. Its boiling point (at normal pressure of 1 ATM), is preferably at least 120°With, preferably, at IU is e, 180°C, preferably is in the range from 200 to 350°With, in particular from 250 to 300°S, more preferably from 260 to 290°C. Expedient is the use of solvents with flash points at normal pressure of 1 ATM, exceeds 110°C. In the General case as absorbents suitable polar organic solvents, for example aliphatic hydrocarbons, which preferably do not contain exerting external influence of polar groups, and aromatic hydrocarbons. In the General case, it is desirable that the absorbent had perhaps a higher boiling point and yet, perhaps, more fully dissolved propane and/or propene. Suitable absorbents are, in particular, aliphatic hydrocarbons, such as alkanes or alkenes with 8-20 carbon atoms, aromatic hydrocarbons, for example, formed during the distillation of paraffin medium fractions, ethers, with voluminous attached to the oxygen atom groups or mixtures of these compounds, and their composition can be added 1,2-dimethylphthalate, as, for example, described in German patent application DE-A 4308087. In addition, suitable esters formed benzoic and phthalic acids and non-branched alkanols with 1 to 8 carbon atoms, in particular n-butyl, methyl and and ethyl ester of benzoic acid, dimethyl or diethyl ester of phthalic acid, and the so-called heat transfer oils, in particular diphenyl, diphenyl ether, a mixture of diphenyl with diphenyl ether or the corresponding chlorinated derivatives and triarylamine, for example 4-methyl-4'-benzylethanolamine and its isomers: 2-methyl-2'-benzyldimethylamine, 2-methyl-4'-benzylbiphenyl, 4-methyl-2'-benzyldimethylamine, and mixtures thereof. Suitable absorbent is a mixture of diphenyl and diphenyl ether, preferably azeotropic composition, in particular, consisting of 25 wt.% of diphenyl (biphenyl) and 75 wt.% diphenyl ether, available under the trade designation devil. Sometimes it adds an additional solvent, such as dimethylphthalate, in the amount of from 0.1 to 25 wt.% (calculated on the total mixture of solvents). Particularly suitable absorbents are also octane, nonanes, decanes, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane and octadecane, particularly suitable are, in particular, tetradecane. Preferably, the used absorbent, on the one hand, possessed above boiling point, and, on the other hand, was not too high molecular weight. Are preferred absorbents, molecular weight which is less than or equal to 300 g/mol. In addition, suitable paraffins is e oil with 8-10 carbon atoms, described in the German patent application DE-A 3313573. For example, suitable series products Haplasol i supplied to the market by the firm Haltermann, in particular Haplasol 250/340 i and Haplasol 250/275 i, as well as oil PKWF and Printosol used in printing inks.

The absorbance can be done without any restrictions, using any known in the art, the methods and conditions. Preferably the contacting of the gas mixture with an absorbent is carried out under a pressure from 1 to 50 bar, preferably from 2 to 20 bar, more preferably from 5 to 10 bar, at a temperature of from 0 to 100°With, in particular from 30 to 50°C. the Absorbance can be in the appropriate columns and apparatus for water quenching unilaterally moving flow or counterflow. Suitable absorption columns are, for example, plate columns with cap and/or sieve plates, columns with structured packings (for example, with a nozzle sheet having a specific surface area of from 100 to 500 m²/m³in particular showerhead Mellapak^®250 Y) and columns filled with the Packed bodies, such as rings process. In addition, there may be used a film and spray columns, absorbers with graphite blocks, surface, in particular, thin - and thick-film absorbers, as well as disc scrubbers, horizontal IC is rubbery with mechanical stirring and rotary scrubbers. In addition, the preferred may be the absorption in a bubble column with inline elements.

The selection of propane and/or propene from the absorbent can be done by steaming, flash evaporation (Flashen) and/or distillation.

Propane and/or propene are separated from the absorbent is preferably carried out at the stage (b) steam or desorption with gas with inert behavior at the stage (C) according to the invention, and/or by molecular oxygen (e.g. air). Steaming can be done 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 2 bar and a temperature of 0 to 200°With, in particular from 20 to 200°S, more preferably from 30 to 50°C. Other gas suitable for the implementation of the steam is, for example, water vapor, however, preferably used, in particular, mixtures of oxygen with nitrogen, for example air. If for steam use air or a mixture of oxygen and nitrogen containing more than 10 vol.% oxygen, before steaming or its implementation, you may want to add gas, limiting the area of the explosion. Especially suitable are gases, heat capacity which at 20°Cerevisae 29 j/mol· To, in particular methane, ethane, propane, butane, pentane, hexane, benzene, methanol, ethanol, and ammonia, carbon dioxide and water. For the implementation of steaming particularly suitable bubble column with inline elements.

Propane and/or propene you can also select from the absorbent by distillation, which can be used are well known in the art columns from the nozzles, nozzle bodies or relevant built-in elements. Preferred are the following distillation conditions: a pressure of from 0.01 to 5 bar, in particular from 0.1 to 3 bar, more preferably from 1 to 2 bar, the temperature in the cube column from 50 to 300°With, in particular from 150 to 250°C.

If the composition of the gas mixture And includes water, preferred is a combination of absorption by moisture condensation (so-called water-quenching, Wasserquench). Preferred is also the implementation of water quenching after the stage of desorption, which allows to minimize the loss of the adsorbent.

Stage (C) often implement directly after stage (b), that is, without performing an intermediate process operations. But it does not exclude the possibility of additional allocation of absorbent between stages (b) and (C)carried out, for example, by water quenching.

Oxidation of propane and/or propene to acrolein and/or acrylic the second acid can be implemented at the stage (C) any known in the art without any restriction, and perhaps one or two stage oxidation of propene to acrolein and/or acrylic acid, the oxidation of propane to acrolein and/or acrylic acid or simultaneous oxidation of propane and propene to acrolein and/or acrylic acid. It is reasonable heterogeneous catalytic gas-phase oxidation with molecular oxygen leading to the mixture of gaseous reaction products containing acrolein and/or acrylic acid. If necessary, supplied to phase oxidation of propane and/or propene is heated to the necessary to carry out the reaction temperature by indirect heat exchange.

The preferred implementation stage (C) of the method according to the invention provides for the oxidation of propene to acrolein and/or acrylic acid.

Heterogeneous catalytic gas-phase oxidation of propene to acrolein and/or acrylic acid by molecular oxygen proceeds in two successive reaction steps, the first of which leads to the formation of acrolein, and the second to the formation of acrylic acid. The reaction in two successive stages provides the possibility of using, in essence, a well-known way to carry out stage (C) of the method according to the invention in two consecutive zones ocil the tion, and used in each of the oxide catalyst can be optimized accordingly. So, in the first oxidation zone (propen → acrolein) is preferred, as a rule, is the use of a catalyst based on a metal oxide containing a combination of molybdenum, bismuth and iron (Mo-Bi-Fe), whereas for the second oxidation zone (acrolein → acrylic acid) are preferred conventional catalysts based on metal oxides containing a combination of molybdenum and vanadium (Mo-V). Used in both reaction zones catalysts based on metal oxides repeatedly described and well known in the art. For example, links to relevant U.S. patents listed on page 5 of European patent application EP-A-0253409. Catalysts suitable for use in both the oxidized zones described in the German patent applications DE-A 4431957 and DE-A 4431949. It is in these documents is, in particular, the compounds of General formula I. the Mixture of products formed in the first oxidation zone is directed into the second oxidation zone is, as a rule, without intermediate processing.

The simplest form of implementation of both zones of oxidation involves the use of shell-and-tube reactor, and the catalyst loading in a separate contact tube in the place of conclusion of the first stage reaction according to the corresponding altered (see, for example, European patent application EP-A-0911313, EP-A-0979813, EP-A-0990636 and German patent application DE-A 2830765). For example, in the corresponding part of the tube instead of the catalyst, if necessary, download inert material.

Preferred, however, is the embodiment of both oxidation zones in the form of two series-connected systems formed by bundles of tubes which can be in General the reactor, and the zone of transition from one beam contact tubes to the other forms of inert outside of the tubes available for the passage of the reaction components of the bulk material. The contact tube, as a rule, washed with brine, while flushing them outside the contact tubes of inert material is missing. Therefore, both beam contact tubes is preferably placed in spatially separated from each other reactors. Between these reactors, as a rule, is placed intermediate the refrigerator to minimize, if necessary, occurring secondary oxidation acrolein contained in the mixture emerging from the first oxidation zone gaseous products. Instead of tubular reactors can also be used to plate reactors-heat exchangers with salt and/or evaporative cooling, for example, described in German patent applications DE-A 19929487 and D-A 19952964.

The reaction temperature in the first oxidation zone generally ranges from 300 to 450°C, preferably from 320 to 390°C. the Reaction temperature in the second oxidation zone generally ranges from 200 to 300°often from 220 to 290°C. the Pressure in both zones of oxidation, it is advisable to maintain in the range of from 0.5 to 5 ATM, preferably from 1 to 3 ATM. The transmission rate of the reaction gas through the oxidation catalysts in both zones of the reactor, measured in nl/l·hour, often ranges from 1500 to 2500 h^-1or up to 4000 h^-1. The transmission rate of propene in nl/l·the hour is often ranges from 50 to 300 h^-1in particular from 100 to 200 hours^-1.

In principle, both the oxidation zone may be of the design described, for example, in German patent applications DE-A 19837517, DE-A 19910506, DE-A 19910508 and DE-A 19837519. Typically, the external temperature control of both zones of oxidation, if necessary, members of the multi-zone reactor systems, known methods result in accordance with a special mixture of gaseous reaction products and downloadable catalyst.

According to the invention it is preferable that in the process according to the invention propane mixed with propene, in the heterogeneous catalytic oxidation behaved like a gas, preferably inert of razbam the indicator.

The total amount of molecular oxygen required for oxidation, can be immediately added to the gas In, but it does not exclude the possibility of additional oxygen at the end of the first oxidation zone.

The molar ratio of propene to molecular oxygen in the first oxidation zone is preferably set in the range from 1:1 to 1:3, often from 1:1.5 to 1:2. The preferred molar ratio of acrolein to molecular oxygen in the second oxidation zone is from 1:0.5 to 1:2.

An excess of molecular oxygen, generally has a preferable effect on the kinetics of gas-phase oxidation in the another reaction zone. Because of heterogeneous catalytic gas-phase oxidation of propene to acrylic acid is subject to kinetic control, propene, in principle, can be used in molar excess with respect to molecular oxygen, for example, that applies to the first oxidation zone, and an excessive amount of propene in fact plays the role of a gaseous diluent.

In principle, heterogeneous catalytic gas-phase oxidation of propene to acrylic acid can be carried out in a single zone of oxidation. In this case, both stages of oxidation implement in a reactor filled with a catalyst capable of catalyzing the other stages of oxidation, and the downloading of catalyst along the reaction coordinate may change gradually or abruptly. In the embodiment, stage (s) in the form of two series-connected zones of oxidation, if necessary, can be partially or completely isolate the carbon dioxide and water vapor formed as by-products in the first zone of oxidation of the mixture leaving the zone gaseous products before you submit them to the second oxidation zone. Preferably choose the method of oxidation, which does not require such a selection.

For the implementation of the reaction stage (C) along with pure molecular oxygen can be used with molecular oxygen diluted with an inert gas, in particular carbon dioxide, carbon monoxide, noble gases, nitrogen and/or saturated hydrocarbons.

It is advisable, at least part needs molecular oxygen to compensate through the use of air as its source. In a preferred embodiment, the gas supplied to the step (C) of the method according to the invention essentially consists only of propane and propene, and as a source of molecular oxygen required for oxidation, use only air. If necessary, by adding to the fed to stage (C) gas In the cold air can facilitate the direct cooling of the gas.

If the target product is acrolein, use the SQL in the second oxidation zone is in the implementation stage (C) is not appropriate.

Oxidation of propene to acrolein and/or acrylic acid in stage (C) can be carried out as described in European patent application EP-A-0117146, U.S. patent US-A-5198578 and US-A-5183936, or similarly, German patent application DE-A 3313573, patent-Canada-CA-A-1217502, U.S. patent US-A-3161670, US-A-4532365 and international application WO 97/36849. Suitable methods of oxidation of propene is also described in European patent applications EP-A-0293224, EP-A-0253409, German patent applications DE-A 4431957, DE-A 4132263 or DE 19508532, and preferred are, in particular, methods of oxidation, involving the use of gaseous diluents.

Oxidation of acrolein to acrylic acid can be carried out in a reactor with a fluidized bed as described in international application WO 00/39065.

Oxidation of propene to acrolein and/or acrylic acid can be carried out also in a plate reactors-heat exchangers described in the German patent application DE-A 19952964.

According to another preferred option stage (C) of the method according to the invention is carried out by oxidation of propane to acrolein and/or acrylic acid in one or more stages in the presence of an appropriate catalyst, and usable are any known in the art ways, one of which is described, for example, in Japanese patent application JP-A-1036311.

Catalysts suitable for heterogeneous catalytic gas-phase oxidation of propane to acrolein and/or acrylic acid is a mixture of oxides of metals of the General formula (I)

in which M¹is tellurium (Te) and/or antimony (Sb),

M²is at least one element from the group including niobium (Nb), tantalum (TA), tungsten (W), titanium (Ti), aluminum (AI), zirconium (Zr), chromium (Cr), manganese (Mn), gallium (Ga), iron (Fe), ruthenium (Ru), cobalt (Co), rhenium (Rh), Nickel (Ni), palladium (Pd), platinum (Pt), lanthanum (La), bismuth (Bi), boron (B), cesium (Cs), tin (Sn), zinc (Zn), silicon (Si) and indium (In)

b is from 0.01 to 1,

C is from 0 to 1, preferably from 0.01 to 1,

d is from 0 to 1, preferably from 0.01 to 1,

n is a number determined by the valency and frequency different from the oxygen elements in the formula (I).

Mixtures of metal oxides, the stoichiometric composition of which corresponds to the formula (I)are known (see, for example, European patent application EP-A-0608838, EP-A-0529853, Japanese patent application JP-A 7-232071, JP-A 10-57813, JP-A 2000-37632, JP-A 10-36311, international application WO 00/29105, Proceedings ISO'99, Sept. 10-11, 1999, G.Centi and S.Perathoner Ed., SCI Pub. 1999, European patent application EP-A-0767164, Catalysis Today 49 (1999), S.141-153, European patent application EP-A-0962253, Applied Catalysis A: General 194-195 (2000), S.479-485, Japanese application paten the JP-A 11/169716, European patent application EP-A-0895809, German patent application DE-A 19835257, Japanese patent application JP-A 8-57319, JP-A 10-28862, JP-A-11-43314, JP-A 11-57479, international patent application WO 00/29106, Japanese patent application JP-A 10-330343, JP-A 11-285637, JP-A 10-310539, JP-A 11-42434, JP-A 11-343261, JP-A 11-343262, international patent application WO 99/03825, Japanese patent application JP-A 7-53448, JP-A 2000-51693 and JP-A 11-263745).

Particularly suitable are described below mixtures of metal oxides (I), (II) and (III).

In mixtures of metal oxides (I) of the formula (I) M¹is tellurium (Te) and/or antimony (Sb); M²is at least one element from the group including niobium (Nb), tantalum (TA), tungsten (W), titanium (Ti), aluminum (AI), zirconium (Zr), chromium (Cr), manganese (Mn), iron (Fe), ruthenium (Ru), cobalt (Co), rhenium (Rh), Nickel (Ni), palladium (Pd), platinum (Pt), bismuth (Bi), boron (b) and cesium (Cs); b is from 0.01 to 1; C is from 0.01 to 1; d is from 0.01 to 1; n is a number determined by the valency and frequency different from the oxygen elements in the composition of the mixture (I).

A mixture of oxides of metals (I) is preferably obtained as follows. A mixture of sources of the elementary constituents of a mixture of oxides of metals (I) is subjected to hydrothermal treatment, highlight the newly formed solid product and by heat treatment make it the active oxide. Preferred is a mixture of oxides of metals (I) next with the tava: M ¹is tellurium (Te), M²is niobium (Nb), b is 0.1 to 0.6, with a equal to 0.05-0.4 and d is from 0.01 to 0.6. The temperature of the heat treatment is preferably from 350 to 700°s, and the initial stage of the heat treatment is carried out, in particular, at a temperature of from 150 to 400°in oxygen-containing atmosphere, and the final stage at a temperature of from 350 to 700°C in an atmosphere of inert gas. Suitable stoichiometric composition of the mixture of metal oxides (I) similar to that shown in European patent application EP-A-0608838, international patent application WO 00/29106, Japanese patent application JP-A 11/169716 and European patent application EP-A-0962253 compositions.

About hydrothermal prior (Deaktivierung) mixtures of metal oxides are well known in the art (see, for example, Applied Catalysis A: 194-195 (2000) 479-485, Kinetics and Catalysis, Vol.40, No.3, 1999, pp.401-404, Chem. Commun., 1999, 517-518, Japanese patent application JP-A 6/227819 and JP-A 2000/26123).

Under hydrothermal processing implies, in particular, heat treatment is preferably thoroughly mixed sources of the elemental constituents of the desired mixture of metal oxides (I)that is made operated under a pressure vessel (autoclave) in the presence of under excessive pressure of water vapor at a temperature of, usually component from more than 100 to 600°the. The pressure is typically up to 500 bar, preferably up to 250 ATM. Temperatures can exceed 600°and the pressure may be above 500 atmospheres, however, from a technological point of view, the use of such a regime marielisabriz. Especially preferred is the hydrothermal treatment carried out with the simultaneous presence of water vapor and condensed water. Such processing may be performed at a temperature of from 100 to more 374,15°C (critical temperature of water) and corresponding pressure. It is reasonable to use this amount of water to allow complete absorption of the parent compounds in the liquid phase with formation of a suspension and/or solution.

It is also possible this way of implementation of the hydrothermal treatment, according to which the thoroughly mixed mixture of the source compounds completely absorbs water condensate in equilibrium with water vapor.

The hydrothermal treatment is preferably carried out at temperatures greater than 100 - 300°C, preferably 150 to 250°With (for example, 160 - 180°). Content sources of elemental constituents of the desired mixture of metal oxides (I) in a mixture of water from these sources in the autoclave, is usually not less than 1 wt.% and usually no more than 90 wt.%. Typical content sources ele is InterNIC components is 3 to 60 wt.% or from 5 to 30 wt.%, often from 5 to 15 wt.%.

The hydrothermal treatment can be carried out both with stirring or without stirring. As a parent compounds (sources of the elemental constituents of a mixture of metal oxides) for hydrothermal treatment is suitable, in particular, any compound that when heated under pressure in the presence of water can form the corresponding oxides and/or hydroxides. For hydrothermal processing can be shared ready oxides and/or hydroxides of elementary components or only some of these oxides and/or hydroxides. The sources of the elemental constituents usually used in fine condition.

As sources of the elemental constituents of any suitable compound that when heated, if necessary, carried out in the presence of air, capable of forming oxides and/or hydroxides. As such starting compounds can be used together ready oxides and/or hydroxides of elementary components or only some of these oxides and/or hydroxides.

Suitable sources of the elemental component containing molybdenum (Mo), are, for example, oxides of molybdenum, in particular molybdenum trioxide, molybdenum salt of the acid, in particular heptamolybdate ammonium, and halides is of molibdeno, in particular chloride molybdenum.

Suitable sources of the elemental component containing vanadium (V)are, for example, venodilatation, vanadium salt of the acid, in particular the ammonium metavanadate, vanadium oxides, in particular vanadium pentoxide (V₂O₅), vanadium halides, in particular vanadium tetrachloride (VCl₄), and oxychloride vanadium, in particular vanadium oxychloride (VOCl₃). As starting compounds, it is advisable to share the vanadium compounds in which vanadium has the oxidation state +4.

Suitable sources of the elemental component containing tellurium, are the oxides of tellurium, in particular tellurium dioxide, metallic tellurium, tellurium halides, in particular tellurium dichloride (TeCl₂), and tellurium acids, in particular ochoterena acid (H₆TeO₆).

The preferred source compounds containing antimony, are the halides of antimony, in particular trichloride antimony (SbCl₃), oxides of antimony, in particular antimony trioxide (Sb₂About₃), antimony acids, in particular HSb(OH)₆and sulphate of oxide of antimony ((SbO₂)SO₄).

Suitable sources of the elemental component containing niobium are, for example, oxides of niobium, in particular niobium pentoxide (Nb₂O₅3), halides of niobium, in particular chloride, niobium (NbCl₅), as well as complex compounds of niobium and organic carboxylic and/or dicarboxylic acids, for example oxalates and the alcoholate of niobium. As a source of niobium is also suitable to be used according to the European patent application EP-A-0895809 solutions containing niobium.

As for the possible source of compounds containing other elements M², it is, above all, about the corresponding halides, nitrate, formate, oxalates, acetates, carbonates and/or hydroxides. Suitable parent compounds are often also oxoproline, such as wolframite or the corresponding acid, and ammonium salts.

Suitable parent compounds, moreover, are polyanion type Anderson described, for example, in the Polyhedron. Vol.6, No.2, pp.213-218, 1987, which were used to obtain the corresponding metal oxide (I), for example, in Applied Catalysis A: General 194-195 (2000) 479-485, or polyanion cited in cited in these publications literary sources. Polyanion type Anderson also described in Kinetics and Catalysis. Vol.40, No.1999, pp.401-404.

Other suitable parent compounds are, for example, polyanion type of Nina Dawson or Keggin. Preferred are such an outcome is s connection which at elevated temperatures in the presence or in the absence of oxygen are transformed into oxides, optionally, gaseous products.

For the implementation of hydrothermal processing usually takes a long time of several hours to several days. Typical duration of the hydrothermal treatment is 48 hours. From a technological point of view, such processing should be performed in an autoclave with an internal Teflon lining. The autoclave before the hydrothermal treatment may be evacuated, if necessary, with simultaneous removal of water in it the mixture. Before you raise the temperature of the autoclave may be filled with inert gas (nitrogen, noble gas). You can also refuse to carry out both of these activities. Water mixture before the hydrothermal treatment can be inititiave by additional purging with an inert gas. The use of these inert gases may be appropriate and from a technological point of view, creating overpressure autoclave before hydrothermal treatment.

Heat treated solid product, highlighted by the completion of the hydrothermal treatment, should be performed at a temperature of from 350 to 700°often when temperature is from 400 to 650° With or from 400 to 600°C, and the autoclave upon completion of the hydrothermal treatment can be cooled to room temperature quickly or slowly, i.e. over a long period of time (for example, without the use of forced cooling). Heat treatment can be performed in oxidise, reducing or inert atmosphere. To create oxidise atmosphere can, for example, to use ordinary air, air enriched or depleted by molecular oxygen. Heat treatment is preferably carried out in an inert atmosphere, that is, for example, in an atmosphere of molecular nitrogen and/or noble gas. Of course, can be performed under vacuum.

If the heat treatment is carried out in a gaseous atmosphere, the treated product may be in the form of a fixed or fluidized bed.

The total duration of the heat treatment may be 24 hours or longer.

Heat treatment is preferably begin in oxidise oxygen-containing atmosphere (e.g. air) at a temperature of from 150 to 400°or from 250 to 350°C. Upon completion of this initial stage it is expedient to continue the heat treatment, exercising it in an atmosphere of inert gas at a temperature of from 350 to 700°from 400 to 650°With whom or from 400 to 600° C. Heat treatment prior catalysts obtained by the hydrothermal treatment may be carried out by tabletting, with subsequent heat treatment and grinding.

From a technological point of view resulting from the hydrothermal treatment, the solid product prior to subsequent heat treatment, it is advisable to be subjected to grinding.

If a mixture of oxides of metals (I) receive from the parent compounds, similar to those used in conventional methods for such mixtures, and heat treatment obtained in the usual way, thoroughly mixed dry mixture is done similarly heat treated solid product obtained by the preliminary hydrothermal processing, while keeping other conditions being equal mixture of metal oxides (I)subjected to hydrothermal treatment, heterogeneous catalytic gas-phase oxidation of propane, generally provide a more selective output of acrylic acid and have a higher catalytic activity.

Mixtures of metal oxides (I) can be used as catalysts as such (for example, powdered or crushed) or in the form of molded products. Catalysis can be performed in a fixed, moving or pseudouridine layer.

Rentgenostrukturnye mixture of metal oxides (I), as a rule, basically the same as the corresponding diffraction patterns presented in the European patent applications EP-A-0529853, EP-A-0608838 and German patent application DE-A 19835247.

Active mixture of metal oxides (I) can also be used in combination with finely dispersed, for example, colloidal materials, in particular silicon dioxide, titanium dioxide, aluminum oxide, zinc oxide, niobium oxide, acting as diluents.

The mass ratio of the diluent to the active mixture can reach up to 9:1, then there may be 6:1 and 3:1. The active mixture can be combined with a diluent prior to heat treatment (annealing) and/or after it. The diluent, usually administered before the hydrothermal treatment. If it is introduced before heat treatment, he must remain in the composition of the calcined mixture that holds true with the introduction of the diluent before the hydrothermal treatment. This condition, for example, as a rule, satisfy calcined at high temperature oxides.

Other suitable for propane oxidation catalysts are mixtures of metal oxides (II)having the above formula (I), with diffraction reflections h, i and k at the corresponding x-ray diffraction peaks are at the diffraction angles (2θ) 2,22±0,4° (h), 27,3±0,4° (i) and 28.2±0,4° (k), PR is what

- diffractive the h reflex is strongest in the diffraction pattern and has a maximum width of 0.5°,

- the intensity of the P_idiffraction reflection i and the intensity of the P_kdiffraction reflex k satisfy the ratio of 0.65≤R≤to 0.85, where R is the intensity ratio defined by the formula R=R_i/(R_i+P_k), and

the half - width of the diffraction reflexes of i and k is ≤1.

Is the preferred value of R that satisfies the relation 0,67≤R≤to 0.75, more preferably an R value of 0.70 to 0.75 or R = 0,72.

It is preferable to use a mixture of oxides of metals (II), where M¹is tellurium (Te). In addition, favored the use of mixtures of oxides (II), where M²is niobium (Nb), tantalum (TA), tungsten (W) and/or titanium (Ti). Preferred are mixtures, where M²is niobium (Nb).

Stoichiometric coefficient "b" in mixtures of metal oxides (II) is preferably from 0.1 to 0.6. The preferred range of values for the stoichiometric coefficient "C" is accordingly from 0.01 to 1, or from 0.05 to 0.4, and the preferred value of the coefficient "d" is in the range from 0.01 to 1 or from 0.1 to 0.6. Especially preferred is the use of such mixtures of oxides is of mallow (II), the values of the stoichiometric coefficients "b", "C" and "d" are within the above preferred ranges. Other suitable stoichiometric compositions of mixtures of metal oxides (II) are quoted above documents, the relevant prior art, in particular in the Japanese patent application JP-A 7-53448.

Purposeful method of producing mixtures of metal oxides (II) are described, for example, in Japanese patent application JP-A 11-43314, according to which such mixtures are recommended for use as heterogeneous catalysts for oxidative dehydrogenation of ethane to Athena.

According to the method described in the cited above documents in accordance with the prior art, first get a mixture of dioxins metals of the formula (I), consisting of i-phase and other phases (e.g., k-phase). The content of the i-phase in the mixture may be increased, for example, by selection of other phases, for example, k-phase, carried out under the microscope, or washing the corresponding liquids, which can be, for example, aqueous solutions of organic acids, in particular oxalic, acetic, citric or tartaric, inorganic acids, in particular nitric acid, alcohols and aqueous solutions of hydrogen peroxide. A method of producing mixtures of dioxins metals (II) described in Japanese patent application JP-A 7-23207.

A mixture of oxides of metals (II) can be obtained by the method described in the German patent application DE-A 198 35247. According to the method of the relevant sources of elemental parts receive more thoroughly mixed, preferably finely dispersed dry mixture, which is subjected to heat treatment at a temperature of from 350 to 700°from 400 to 650°or from 400 to 600°Stepovoy processing can be performed in oxidise, reducing or inert atmosphere. To create oxidise atmosphere using, for example, conventional air and air enriched or depleted by molecular oxygen. Heat treatment is preferably carried out in an inert atmosphere, for example in an atmosphere of molecular nitrogen and/or noble gas. It is usually carried out at normal pressure (1 ATM). Of course, the heat treatment may be carried out under vacuum or under reduced pressure.

If heat treatment using gaseous atmosphere, it can be implemented in a fixed or fluidized bed. Heat treatment in total may take 24 hours or longer.

Heat treatment is preferably begin in oxidise oxygen-containing atmosphere (e.g. air) at a temperature of from 150 to 400°and the and from 250 to 350° C. Upon completion of the initial stage it is expedient to continue the heat treatment in the atmosphere of inert gas at a temperature of from 350 to 700°from 400 to 650°or from 400 to 600°Stalowa pre-processing catalysts obtained by the hydrothermal treatment may be carried out as follows. First they tabletirujut, if necessary, pulverized to a powder (tableting produce, if necessary, with addition of from 0.5 to 2 wt.% fine graphite), and then subjected to heat treatment and re-grinding.

Starting compound to obtain mixtures of metal oxides (II) can be mixed in a dry or wet condition. If you carry out dry mixing, the parent compound should be used in the form of a fine powder, and after mixing and, if necessary, seal subjected to calcination (heat treatment). Preferred, however, is the mixing in the wet state, and the initial compounds are usually in the form of an aqueous solution and/or suspension. Obtained by mixing the aqueous mixture is dried and calcined. Under water mixture is preferably meant an aqueous solution or aqueous suspension. Drying is preferably carried out directly by p the following receiving water mix in direct-flow or counter-current spray dryer (temperature at the exit of the dryer, usually ranges from 100 to 150°), and especially thoroughly mixed dry mixture is produced primarily in the case enters the dryer water mixture is an aqueous solution or aqueous suspension.

As starting compounds to obtain a mixture of metal oxides (II) (sources of elementary components) described above is suitable compounds designed to obtain mixtures of oxides (I).

Use a mixture of oxides of metals (II) and obtain the corresponding molded articles can be similarly described above, mixtures of metal oxides (I). A mixture of oxides of metals (II) can be subjected to molding, for example, by coating on a substrate, as described below for mixtures of metal oxides (III), extrusion and/or tabletting in fine condition, which can be subjected to and also fine pre-mixed oxide (II).

A mixture of oxides of metals (II) can also be used like mixtures of oxides (I) in dilute fine material condition.

The catalysts based on mixtures of metal oxides (II) can be given the form of spherical particles, solid cylinders or rings (hollow cylinders), the longitudinal size of which typically ranges from 1 to 10 mm Length of the cylinder is preferably from 2 to 10 mm, outer Diametric 4 to 10 mm The wall thickness of the rings is usually from 1 to 4 mm, Suitable calceolaria catalyst particles may also have the following geometrical parameters: length from 3 to 6 mm, an external diameter of from 4 to 8 mm and wall thickness from 1 to 2 mm Along with this does not preclude the possibility of using a ring-shaped particles with parameters 7 mm × 3 mm × 4 mm or 5 mm × 3 mm × 2 mm (external diameter × length × inner diameter).

The intensity of the diffraction reflexes on the corresponding x-ray diffraction pattern described in the German patent applications DE-A 19835247, DE-A 10051419 and DE-A 10046672.

That is, if a¹mean peak diffraction reflex 1, In¹means the nearest minimum, shown to the left of the peak And¹on-line x-ray diffraction pattern, when viewed along the axis intensity perpendicular to the axis 2θ (shoulders diffraction reflexes are not taken into account),²means the nearest minimum, shown to the right of the peak And¹and With¹means the point at which a straight line drawn from the peak And¹perpendicular to the axis 2θcrosses the line connecting the points In¹and²the intensity of the diffraction reflex 1 is determined by the length of a segment of a straight And¹connecting the peak And¹point With¹. At least in this case means the point is, in which the gradient of the slope of the tangent to the curve at the base of the diffraction reflex 1 changes the value from negative to positive, or the point at which the gradient of the slope passes through zero, and to determine the gradient of the slope using coordinates axis 2θ and axis intensity.

The width in this case is the length of a segment of straight line formed between the points of intersection of N¹and N²if in the middle of the segment And¹C¹to draw a line, parallel to the axis 2θand N¹and N²respectively are the first points of intersection of this parallel line with the above line x-ray diffraction left and right of the peak And¹.

Example determine the half-width and intensity are presented on Fig.6 German patent application DE-A 10046672.

Along with the diffraction reflections h, i and k on the x-ray diffraction pattern of the preferred catalytically active mixtures of metal oxides (II)generally, you can find additional reflexes, peaks which correspond to the following diffraction angles (2θ):

9,0±0,4° (l)

6,7±0,4° (o) and

7,9±0,4° (R).

Preferably, if the x-ray diffraction pattern of the catalytically active mixtures of oxides of the General formula (I) present additional diffractive reflector is with, the top of which corresponds to the diffraction angle (2θ):45,2±0,4° (q).

X-ray diffraction pattern of mixtures of metal oxides (II) it is often possible to detect also the reflexes 29,2±0,4° (m) and 35.4±0,4° (n).

X-ray diffraction pattern of some mixtures of metal oxides (II) may not be diffraction reflex, the peak of which corresponds to the angle 2θ=50,0±0,3°that indicates the absence of such mixtures of k-phase.

However, a mixture of oxides of metals (II) may contain k-phase, and x-ray diffraction pattern, as a rule, manifest and other reflexes, peaks which correspond to the angles of diffraction (2θ):

36,2±0,4° and

50,0±0,4°.

If we take the intensity of the diffraction reflex h at 100, preferably below the diffraction reflexes i, i, m, n, o, p, q according to the corresponding scale had the following intensity values:

i: from 5 to 95, frequently from 5 to 80, in particular from 10 to 60;

l: from 1 to 30;

m: from 1 to 40;

n: from 1 to 40;

a: from 1 to 30;

R: from 1 to 30 and

q: from 5 to 60.

If the x-ray diffraction pattern are present above additional reflexes, their width, as a rule, is less than or equal to 1°.

All of the above data refer to the x-ray diffraction patterns obtained using R is thenewschool radiation Cu-Ka (Siemens diffractometer Theta-Theta D-2000, the voltage of the tube 40 kV, tube current 40 mA, aperture aperture V20 (variable), aperture scattering V20 (variable), secondary aperture of the monochromator (0.1 mm), the aperture of the detector (0.6 mm), measuring interval (2θ) 0,02°, measurement time per step) of 2.4 seconds, acquired scintillation counter as a detector).

The specific surface of mixture of metal oxides (II) often is from 1 to 30 m²/g (BET method, nitrogen atmosphere).

For propane oxidation is also suitable catalyst (III), which is a catalytically active mixture of metal oxides of the above formula (I), applied to the surface of the substrate.

It is preferable to use mixtures of the oxides of the General formula (I), where M¹is tellurium (Te). As M²preferred niobium (Nb), tantalum (TA), tungsten (W) and/or titanium (Ti). It is preferable to use as M²niobium (Nb).

Preferred the following values of the stoichiometric coefficients for a mixture of oxides of General formula (I) in the catalyst (III): "b" of 0.1 to 0.6, with from 0.01 to 1, or from 0.05 to 0.4 and d from 0.01 to 1 or from 0.1 to 0.6. Especially preferred are mixtures of the oxides, the stoichiometric coefficients "b", "C" and "d" which simultaneously are within the above preferred ranges.

The others who zgodnie stoichiometric compositions of mixtures of oxides of the General formula (I) described in the above documents, in particular in the European patent applications EP-A-0608838, EP-A-0962253, international patent application WO 00/29106 and Japanese patent application JP-A 11/169716.

Especially preferred is also obtaining a catalyst (III) by applying the above-described mixtures of metal oxides (II) as mixtures of oxides having the formula (I), to the appropriate media.

The carriers are preferably chemically inert materials, i.e., they mostly do not participate in the course of the catalytic gas-phase oxidation of propane to acrylic acid. As the material of the carrier can be used, for example, aluminum oxide, silicon dioxide, silicates, in particular clay, kaolin, steatite, pumice, aluminum silicate and magnesium silicate, silicon carbide, oxide of zinc, thorium dioxide.

The surface of the particle carrier may be smooth or rough. Preferred carriers are having a rough surface, because the surface roughness enhances adhesion of the deposited active mixture of oxides.

The surface roughness R_zthe media is often in the range of from 2 to 200 microns, in particular in the range from 20 to 100 μm (definition of roughness according to DIN 4768, sheet 1, using tester Homes for measurement of surface parameters according to DIN-ISO, produced by Hommelwerke, Germany).

On the poison with this media may have a porous or monolithic structure. Expedient is the use of monolithic carrier with respect to the total pore volume to the volume of media that is less than or equal to 1%vol.

The thickness of the shell formed on the carrier surface active mixture of metal oxides, is preferably from 10 to 1000 μm. It can range from 50 to 700, 100 to 600, 300, 500 or 150 to 400 μm. Possible is also the shell thickness from 10 to 500, 100 to 500 or 150 to 300 microns.

In principle, the carrier particles may have any geometrical parameters, wherein the longitudinal size typically ranges from 1 to 10 mm are Preferred carriers in the form of spherical or cylindrical particles, in particular in the form of hollow cylinders (rings). The preferred diameter of the spherical particles of the medium is 1.5 to 4 mm, If the carrier particles have a cylindrical shape, their length is preferably from 2 to 10 mm, the outer diameter is preferably from 4 to 10 mm, the wall Thickness of the annular carrier particles is usually from 1 to 4 mm, Suitable annular particles may have a length of from 3 to 6 mm, an external diameter of from 4 to 8 mm and wall thickness from 1 to 2 mm Can be used as a carrier in the form of particles with geometric parameters 7 mm × 3 mm × 4 mm or 5 mm × 3 mm × 2 mm (external diameter × length × inner diameter).

the Simplest way to obtain a catalyst (III) is in active preparation of mixtures of oxides of the General formula (I), their translation in fine condition and coating the surface of the particles of the medium through the liquid binder. For this purpose, the surface of the particles hydrate liquid binder, on wetted surfaces in a contactless manner fixed layer of micronized active compounds oxides of the General formula (I), followed by drying of the particles of media coverage. Repeatedly repeating the described process can be applied more and more layers, receiving media with increased coating thickness.

The dispersion applied to the surface of the carrier particles of the catalytically active mixed oxide of General formula (I) is selected depending on the desired thickness of the coating. For shells with a thickness of 100 to 500 μm is suitable, for example, a powder of the active mixture, at least 50% of particles from the total amount which pass through a sieve with openings of 1 to 20 μm, and the content of particles with a longitudinal size exceeding 50 μm is less than 10%. The dispersion of particles of powder mixtures of oxides defined by the magnitude of the longitudinal dimension, usually described by a Gaussian distribution, due to the way they are received.

The above-described method of coating medium in a technical scale is recommended, using, for example, described in German patent application DE-A 2909671 technology is systematic principle. This means that the media, which should be coated, load in rotating preferably at an angle capacity, for example in a rotating disk storage tank or pelleting drum, and the angle of inclination (the angle between the Central axis of the rotating container and the horizontal plane)typically ranges from 0 to 90°most often from 30 to 90°. Located in a rotating tank carrier in the form of particles having, for example, spherical or cylindrical shape, passes under two located at a certain distance from each other dosing devices. It is advisable that by the first of the dispenser, which is a nozzle (for example, driven by compressed air spray nozzle), was carried out spraying liquid binder to the surface of carrier particles, rolling on a rotating plates, with simultaneous control of the degree of hydration.

The second metering device is located outside the cone of the spray of liquid binder and serves to supply finely dispersed active mixture of oxides, for example, by swinging the chute or auger. The particles of the medium, for example, spherical or cylindrical shape, moistened in a controlled amount of liquid binder, absorb dosing of powdery active is mesh, which is condensed on the outer surface of the particles, forming a strongly attached to her shell.

If necessary, the particles of the medium created in the way described above the coating layer with the continued rotation of the tank again pass under the spray nozzle, where they are subjected to a controlled moisture, so that during further movement was possible to apply an extra layer of micronized active compounds oxides, and this process can be repeated many times (intermediate drying medium, usually not needed). A fine mixture of oxides and liquid binder at the same time, usually served continuously and synchronously.

Excess liquid binder can be removed upon completion of the coating, for example, by blowing medium hot gases, in particular hot nitrogen or air. It should be noted that the described method of coating provides excellent mutual adhesion of the successively applied layers and excellent adhesion of the base layer with the surface of the carrier.

An important feature of the above-described method of coating is that the wetting of the surface of carrier particles provide a controlled way. That is, the surface of the particles of the medium it is recommended to hydrate so that the liquid binder adsorbiroval is it without formation of a liquid phase, which would be noticeable by visual observation. Too heavy wetting the surface of the medium leads to the aggregation of fine particles of catalytically active mixture of oxides in the agglomerates instead of their uniform distribution over the surface of the particles. More detailed information on this issue is presented in the German patent application DE-A 2909671.

The above-mentioned removal of the liquid binder can be carried out in a controlled way, for example, by evaporation and/or sublimirovanny. In the most simple case, the binder can be removed by purge carrier gas, heated to the appropriate temperature, often a component of from 50 to 300°With, in particular 150°C. Due to the effect of hot gases can be carried out and the preliminary drying of the media. The final drying of the carrier can be produced in drying furnaces of any type, for example in a belt dryer, thus affecting the media temperature must not exceed the temperature at which annealing (heat treatment) upon receipt of an active mixture of oxides. Drying can also be produced using only a drying oven.

The type of binder used for applying the coating depends on the type and geometrical parameters of the particles of the medium. As the binder can use is to water, monovalent alcohols, in particular ethanol, methanol, propanol and butanol, polyvalent alcohols, in particular ethylene glycol, 1,4-butanediol, 1,6-hexanediol or glycerol, one - or polyvalent carboxylic acids, particularly propionic, oxalic, malonic, glutaric, or maleic acid, inospiti, in particular ethanolamine or diethanolamine, as well as one - or polyvalent organic amides, in particular formamid. Preferred binders are also solutions consisting of water (from 20 to 90 wt.%) and dissolved organic compounds (from 10 to 80 wt.%), boiling point or sublimation of which at normal pressure (1 ATM) exceeds 100°C, preferably 150°C. the Organic compound is preferably selected from the above list of possible organic binder. The preferred content of organic compounds in said aqueous binder is from 10 to 50 wt.%, particularly preferably 20 to 30 wt.%. As organic components suitable monosaccharides and oligosaccharides, in particular glucose, fructose, sucrose or lactose, as well as oxides and polyacrylates.

The catalytically active mixed oxide of General formula (I) can be obtained by known methods described in the above-cited documents according to the level of the Yu technology. This means that they can be obtained, for example, as hydrothermal and conventional methods.

In the latter case, the catalytically active mixed oxide of General formula (I) receive, preparing of relevant sources of elemental parts as possible thoroughly mixed, preferably finely dispersed dry mixture and subjecting it to heat treatment at a temperature of from 350 to 700°from 400 to 650°or from 400 to 600°C. Heat treatment and thorough mixing of the starting compounds can be produced similarly to the above method of obtaining a mixture of metal oxides (II).

In the framework of the above-described method of producing a catalytically active mixtures of metal oxides with the General formula (I) as sources of elemental parts suitable starting compound, which is used to produce the above-described mixture of metal oxides (I).

Particularly preferred catalysts are the media with a coating consisting of a mixture of oxides of metals (II) as the catalytically active mixed oxide of General formula (I).

To obtain catalysts coated with suitable active compounds oxides of the General formula (I)described in the international patent application WO 00/29106 and with a predominantly amorphous structure, which is found on the x-ray difractogram the IU in the form of very broad diffraction reflexes with peaks in the area of angles of diffraction (2θ ) 22° and 27°.

Suitable are also active mixture of oxides of the General formula (I)described in European patent applications EP-A-0529853 and EP-A-0608838, x-ray diffraction patterns which are very narrow diffraction reflexes with peaks in the area of angles of diffraction (2θ) 22,1±0,3°, 28,2±0,3°, 36,2±0,3°, 45,2±0,3° and 50.0±0,3°.

Catalysts in the form of media coverage can be obtained not only by drawing on the wetted surface of the particles of the medium are ready micronized active mixtures of oxides of the General formula (I), but also by drawing on the prepared similarly the surface of the fine pre-mixtures of oxides carried out in a similar way using the same binder and calcination of the carrier coated with a coating after pre-drying. Fine pre-mixture of oxides can be obtained, for example, as follows. First of springs elementary components of the active mixture of oxides of the General formula (I) of the desired composition may receive more thoroughly mixed fine dry mixture (for example, by spray drying aqueous suspension or solution of the sources of the elemental constituents), and then this mixture for several hours put Joe the th treatment (if necessary, after tableting, carried out with the addition of finely dispersed graphite in an amount of from 0.5 to 2 wt.%) at a temperature of from 150 to 350°C, preferably from 250 to 350°in oxidise oxygen-containing atmosphere (e.g. air) and, if necessary, grinding. After applying to the particles of the carrier pre-mix them preferably calcined in an atmosphere of inert gas (you can use any other atmosphere) at a temperature of from 360 to 700°from 400 to 650°or from 400 to 600°C.

The above-described mixture of metal oxides (II) or catalysts (III) in combination with a mixture of metal oxides (II) as catalytically active compounds can also be used for the oxidation of propene, which can be done in the presence of propane, plays the role of a gaseous diluent, although part of him and can be oxidized to acrylic acid.

Oxidation of propane can be carried out by any known specialists of ways without any restrictions, for example by the method described in European patent application EP-A-0608838 or international patent application WO 00/29106. This means that the gas supplied to the step (C) for catalytic oxidation is carried out at a temperature of, for example, from 200 to 550°from 230 to 480°or from 300 to 440°may have, for example, as compiled by the PTO:

Other possible compositions of the gas mixture supplied to the step (C) are, in particular, the following:

For propane oxidation is also suitable are described in the German patent application DE-A 199 52964 plate reactors-heat exchangers. According to another variant implementation of the invention, the oxidation of propane implement the methods described in the German patent applications DE-A 19837517, DE-A 19837518, DE-A 19837519 and DE-A 19837520.

In the composition of the reaction mixture resulting from the oxidation of propene and/or propane at the stage (C) by the method according to the invention, along with the predominantly contained within the target products, i.e. acrolein and/or acrylic acid, as a rule, are neprevyshenie molecular oxygen, propane and propene, molecular nitrogen, water vapor and carbon dioxide formed as a by-product and/or used is as gaseous diluents, and small quantities of low molecular weight aldehydes, hydrocarbons and other inert gateopener thinners.

Target products (acrolein and/or acrylic acid can be separated from a mixture of oxidation products by known methods, for example by azeotropic distillation, fractional distillation, carried out in the presence of a solvent or without it, or crystallization.

For example, suitable methods of allocation are partial condensation of acrylic acid, its absorption by water or high-boiling hydrophobic organic solvent or absorption acrolein water or aqueous solutions of low molecular weight carboxylic acids with subsequent processing of absorbate. An alternative method of selection of target products from the reaction mixture is fractionated condensation (see, for example, European patent application EP-A-0117146, German patent application DE-A 4308087, DE-A 4335172, DE-AND 4436243, DE-A 19924532 and DE-A 19924533.

According to a particularly preferred variant of the process according to the invention neprevyshenie at the stage (C) propane and/or propene separated from remaining after separation of the target product gas mixture, implementing stage (a) and (b), and again return them to the stage (s).

The gas mixture As used in stage (a) of the method according to the invention may have a composition similar to the composition of the gas mixture, the resulting catalytic dehydrogenation of propane to propene. Moreover, the dehydrogenation of propane can be oxidizing, that is carried out with addition of oxygen or without the addition of oxygen, in particular, mostly without adding oxygen. If we are talking about dehydration with the addition of oxygen, there are two possible options. In the first variant, all the formed hydrogen is oxidized through the use of excessive amounts of oxygen, resulting in hydrogen is completely absent in the gaseous dehydrogenation products, but they contain excess oxygen (oxidative dehydrogenation). In the second embodiment, oxygen is supplied only in the amount needed to compensate for thermal effect of the reaction, therefore, the oxygen in the gaseous reaction products is completely absent, however, they contain hydrogen (autothermal process). Dehydrogenation of propane may be catalytic or non-catalytic (homogeneous) method.

The propane dehydrogenation can be carried out, for example, as described in the German patent application DE-A 3313573 and European patent application EP-A-0117146.

In principle oxidative dehydrogenation can be carried out in a homogeneous and/or heterogeneous oxidisation of propane to propene with use is the use of molecular oxygen.

If this is the first step of the reaction is homogeneous oxidative dehydrogenation, in principle it can be implemented as described in U.S. patent US-A-3798 283, Chinese patent application CN-A-1105352, Applied Catalysis, 70(2), 1991, S.175-187, Catalysis Today 13, 1992, S.673-678, and German patent application DE-A-19622331, and as the source of oxygen can be used as the air.

Suitable temperature interval homogeneous oxidative dehydrogenation is from 300 to 700°C, preferably from 400 to 600°S, especially preferably from 400 to 500°C. the Operating pressure may be from 0.5 to 100 bar, in particular from 1 to 10 bar. The time is usually from 0.1 or 0.5 to 20 seconds, preferably from 0.1 or 0.5 to 5 sec. As the reactor can be used, for example, a tube furnace or shell-and-tube reactor, for example counterflow tube furnace with flue gas as a coolant or shell-and-tube reactor with salt melt as the heat carrier. The ratio of propane : oxygen in the gas mixture leaving the reactor is preferably from 0.5:1 to 40:1, in particular from 1:1 to 6:1, more preferably from 2:1 to 5:1. The gas mixture may contain other, mostly inert components, in particular water, carbon dioxide, carbon monoxide, nitrogen, noble gases and/or propene, this may itii about the return to the step (a) components, which in General is designated as the recirculated gas.

If the propane dehydrogenation is carried out in the form of heterogeneous catalytic oxidative dehydrogenation, in principle, it can be implemented, as described, for example, in U.S. patent US-A 4788371, Chinese patent application 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, international patent application WO 97/36849, German patent application DE-A 19753817, U.S. patent US-A 3862256 and US-A 3887631, German patent application DE-A 19530454, U.S. patent US-A 4341664, J. of Catalysis 167, 560-569 (1997), J. of Catalysis 167, 550-559 (1997), Topics in Catalysis 3 (1996), 265-275, U.S. patent 5086032, Catalysis Letters 10 (1991), 181-192, Ind. Eng. Chem. Res. 1996, 35, 14-18, U.S. patent US-A 4255284, Applied Catalysis A.: General, 100 (1993), 111-130, J. of Catalysis 148, 56-67 (1994), V.Cortes Corberan und S.Vic.Bellon (Ed.), New Developments in Selective Oxidation II, 1994, Elsevier Science B.V., S.305-313, 3^rdWorld Congress on Oxidation Catalysis, R.K. Grasselli, S.T. Oyama, A.M.Gaffney and J.E.Lyons (Ed.), 1997, Elsevier Science B.V., S.375 ff. As the oxygen source, you can use the air, however, it is preferable source containing at least 90 mol.% oxygen, more preferably 95 mol.% oxygen (relative to the origin, containing 100 mol.% oxygen).

For heterogeneous catalytic oxidative dehydrogenation without any special restrictions any suitable, well-known specialists in the field of chemical technology catalysts capable of catalyzing the oxidation of propane to propene. In particular, can be any, given in the above documents catalysts for oxidative dehydrogenation. Preferred are, for example, a mixture of oxides of molybdenum, vanadium and niobium or Vandalproof used together with the promoter. Particularly suitable catalyst is, for example, a mixture of metal oxides containing as the main components of molybdenum (Mo), vanadium (V), tellurium (Te), oxygen (O) and X, and X represents at least one element selected from the group comprising niobium, tantalum, tungsten, titanium, aluminum, zirconium, chromium, manganese, iron, ruthenium, cobalt, rhodium, Nickel, palladium, platinum, antimony, bismuth, boron, indium and cerium. In addition, particularly suitable catalysts for the oxidative dehydrogenation are a mixture of several oxides of metals or catalysts As described in the German patent application DE-A-19753817, and a mixture of oxides of metals or catalysts As indicated in this application as the preferred, have a particularly favorable catalytic action. This means that as the active compounds are used, in particular, a mixture of several metal oxides (IV) of General formula IV

in which M¹is cobalt (Co), Nickel (Ni), magnesium (Mg), zinc (Zn), manganese (Mn) and the and copper (Cu),

M²is tungsten (W), vanadium (V), tellurium (Te), niobium (Nb), phosphorus (P), chromium (Cr), iron (Fe), antimony (Sb), cesium (Cs), tin (Sn) and/or lanthanum (La),

as well as 0.5 to 1.5,

b is 0-0,5,

x is a number determined by the valency and frequency different from the oxygen elements in the formula (IV).

Suitable active compounds (IV) can, in principle, be obtained in the following simple way. From a suitable source of elemental parts receive more thoroughly mixed, preferably finely dispersed dry mixture required stoichiometric composition and calcined her at a temperature of from 450 to 1000°C. as sources of elemental constituents of the active mixtures of metal oxides (IV) use the oxides and/or compounds that, by heating, which is provided, at least in the presence of oxygen, capable of being converted into oxides. It is first and foremost about the halides, nitrate, formate, oxalate, citrate, carbonate, complex aminollah, ammonium salts and/or hydroxides. Thorough mixing of the starting compounds to obtain mixtures of metal oxides (IV) can be performed by a dry process, for example, using an appropriate fine powders, or a wet method, for example, in the presence of water as solvent. A mixture of the oxide is in metals (IV) can be used in the powdered state or in the form of shaped particles, with certain geometrical parameters, and the shaping may be effected before or after the annealing. Can be used full or powdered catalysts active or pre-mixture of oxides can be given a definite shape by drawing on pre-formed inert carrier. The material of the carrier may be conventional porous or solid oxides of aluminium, silicon dioxide, thorium dioxide, dioxide, zinc, silicon carbide or silicates, and the carrier particles may have a right or wrong form.

The temperature of the heterogeneous catalytic oxidative dehydrogenation of propane preferably lies in the range from 200 to 600°With, in particular in the range from 250 to 500°S, more preferably in the range of from 350 to 440°C. the Operating pressure is preferably from 0.5 to 10 bar, in particular from 1 to 10 bar, more preferably from 1 to 5 bar. Especially preferred is the working pressure of over 1 bar, for example from 1.5 to 10 bar. Heterogeneous oxidative dehydrogenation of propane is produced using, as a rule, the fixed catalyst bed, which according to an expedient variant of the method is loaded into the tube shell-and-tube reactor as described, for example, in European patent applications EP-A-0700893 THE EP-A-0700714, and cited in these applications the literature. Suitable average residence time of the reaction mixture in the catalyst layer is from 0.5 to 20 sec. The ratio of propane to oxygen varies depending on the desired degree of conversion of propane and selectivity of the catalyst, and a suitable ratio is from 0.5:1 to 40:1, in particular from 1:1 to 6:1, more preferably from 2:1 to 5:1. The selectivity of the output of propene with increasing degree of conversion of propane, as a rule, decreases, and therefore the propane dehydrogenation is preferably carried out in such a way as to ensure high selectivity yield of propene with relatively low degrees of conversion of propane. Especially preferred degree of conversion of propane corresponds to the interval from 5 to 40%, more preferably from 10 to 30%, in this case, the degree of transformation implies that part of the propane from its total input quantity, which is undergoing transformation. Especially preferred selectivity corresponds to the interval from 50 to 98%, more preferably from 80 to 98%, and the term "selectivity" means the ratio of the number of moles of propene obtained to the number of moles converted propane.

100 wt.% the initial mixture used for the oxidative dehydrogenation of propane, preferably contain from 5 to 9 wt.% propane. The original mix along with propane and oxygen can contain other, in particular, inert components, such as water, carbon dioxide, carbon monoxide, nitrogen, inert gases and/or propene. Heterogeneous oxidative dehydrogenation can be performed in the presence of diluents, for example water vapor.

Both homogeneous and heterogeneous catalytic oxidative dehydrogenation can be carried out in any known specialists sequence. For example, the dehydrogenation can occur in one, two or several stages, between which carry oxygen. In addition, there is the possibility of combining homogeneous and heterogeneous catalytic oxidative dehydrogenation.

Possible components of the reaction mixture resulting from the oxidative dehydrogenation of propane, are, for example, the following substances: propene, propane, carbon dioxide, carbon monoxide, water, nitrogen, oxygen, ethane, Aten, methane, acrolein, acrylic acid, ethylene oxide, butane, acetic acid, formaldehyde, formic acid, propylene oxide and butene. 100 wt.% the mixture of products obtained by the oxidative dehydrogenation of propane, preferably contains from 5 to 10 wt.% of propene, 1 to 2 wt.% carbon monoxide, from 1 to 3% m is C, carbon dioxide from 4 to 10 wt.% water, from 0 to 1 wt.% nitrogen, from 0.1 to 0.5 wt.% acrolein, from 0 to 1 wt.% acrylic acid, from 0.05 to 0.2 wt.% acetic acid, from 0.01 to 0.05 wt.% formaldehyde, 1 to 5 wt.% oxygen, from 0.1 to 1.0 wt.% other above components, in particular the residual propane.

In the General case, the gas mixture may be obtained by heterogeneous catalytic dehydrogenation of propane, mainly carried out in the presence of excess oxygen, as described in the German patent application DE-A 3313573 or below.

Because the dehydration is accompanied by a volume increase, the degree of conversion of propane can be improved by reducing its partial pressure. The easiest way to achieve this goal can be, for example, the implementation of the dehydrogenation of propane under reduced pressure and/or introduction of the source gas of predominantly inert gaseous diluents, for example water vapor, which under normal dehydrogenation behaves like an inert gas. An additional advantage of the dilution of propane steam is, as a rule, reducing coking of the catalyst dehydrogenation, because the water vapor reacts with the formed coke on the principle of coal gasification. In addition, water vapor can serve as gaseous rasb is representative of the mixture, supplied to the subsequent oxidation (stage (C)). Along with this water vapor can be partially or completely separate from the gas mixture supplied to the step (C), for example, by condensation that provides the ability to increase the content in this mixture of nitrogen, is used as a gaseous diluent. Other suitable for propane dehydrogenation of gaseous diluents are, for example, carbon monoxide, carbon dioxide, nitrogen and noble gases, particularly xenon, neon and argon. These gaseous diluents can be used separately or in mixture with each other. In the preferred embodiment, they are generally suitable for dilution supplied to the step (C) of the gas mixture. In the General case, it is preferable to use for the implementation of appropriate reaction inert gaseous diluent (valid chemical change of the diluent is less than 5 mol.%, is preferably not more than 3 mol.% and more preferably not more than 1 mol.%). For dehydrogenation of propane in principle any suitable dehydrogenation catalysts according to the prior art, which roughly can be divided into two following groups. The first group consists of the catalysts having the oxide nature, such as chromium oxide and/or aluminum oxide. The second group is made up of kata is history, representing at least one, typically a noble metal (e.g. platinum)supported on a carrier, typically representing the oxide.

Along with other can be used in the dehydrogenation catalysts recommended in the international patent application WO 99/46039, U.S. patent US-A 4788371, European patent application EP-A-0705136, international patent WO 99/29420, U.S. patent US-A 4220091, US-A 5430220 and US-A 5877369, European patent application EP-A-0 117146, German patent applications DE-A 19937196, DE-A 19937105 and DE-A 19937107. In particular, can be used with the catalysts prepared according to examples 1, 2, 3 and 4 presented in the German patent application DE-A 19937107.

It is about the dehydrogenation catalysts containing from 10 to 99.9 wt.% dioxide zinc, from 0 to 60 wt.% aluminum oxide, silicon dioxide and/or titanium dioxide and from 0.1 to 10 wt.%, at least one element from the first and second main groups, one element from the third subgroup, one element of the eighth subgroup of the periodic system of the elements, lanthanum and/or tin, provided that the relevant amount is 100 wt.%.

For dehydrogenation of propane in principle any suitable corresponding to the prior art reactor types and variants of the method. Description of these options are given, for example, all documents related to katal the congestion dehydrogenation according to the prior art.

A fairly detailed description of a suitable method of dehydrogenation according to the invention is also provided in "Catalytical Studies Division, Oxidative Dehydrogenation and Alternative Dehydrogenation Processes, Study Number 4192 OD, 1993, 430 Ferguson Drive, Mountain View, California, 94043-5272, USA.

A characteristic feature of partial heterogeneous catalytic dehydrogenation of propane is indeterminate. This means that heat (thermal energy)required to establish the desired reaction temperature should be fed to the reaction gas to the implementation of catalytic dehydrogenation and/or in its course.

Along with this characteristic feature of heterogeneous catalytic dehydrogenation of propane, requiring the use of high temperatures is the formation of small amounts of taglocity high-molecular organic compounds, up to carbon, which form deposits on the catalyst surface, leading to its deactivation. To minimize this undesirable side effect, propane supplied to the surface of the catalyst dehydrogenation is carried out at elevated temperature, can be diluted with water vapor. These conditions result in partial or complete elimination of carbon deposits in accordance with the principle underlying the gasification of coal.

Another possibility of removal of sediments, formed by the hydrocarbon compounds, is that through the dehydrogenation catalyst at elevated temperature periodically transmit the oxygen-containing gas, thanks to a certain part of the deposits of carbon burned.

Reduce the formation of carbon deposits can also, by entering in the composition of the subject catalytic dehydrogenation of propane with molecular hydrogen before miss propane through heated to a high temperature dehydrogenation catalyst.

In addition, there is the possibility of adding a subject to the catalytic dehydrogenation of propane a mixture of water vapor and molecular hydrogen. Adding molecular hydrogen also contributes to the suppression of the unwanted formation of these side products of the catalytic dehydrogenation of propane, as Allen and acetylene.

Suitable reactor for effecting the dehydrogenation of propane is a shell-and-tube reactor with a fixed bed of the catalyst loaded in a single tube or bundle of tubes. Heating of the reaction tubes is carried out, burning in the surrounding volume of combustible gas, such as hydrocarbons, in particular methane. This direct method preferably should be heated only the first 20-30% of the fixed catalyst layer placed in contact tube. The necessary reaction temperature in the rest of the tubes should be maintained for the odd use of funds allocated by burning combustible gas radiant heat. Thanks to this method of heating can be provided practically isothermal dehydrogenation conditions. Suitable diameter of the reaction tubes is from 10 to 15 cm of a Typical shell-and-tube reactor for the dehydrogenation contains from 300 to 1000 reaction tubes. The temperature inside the tubes is from 300 to 700°C, preferably from 400 to 700°C.

It is preferable heating supplied to the tubular reactor, the reaction gas to the reaction temperature. The temperature of the mixture leaving the reactor products is often 50-100°below the reaction temperature. To implement the above method, the oxidative dehydrogenation appropriate use of catalysts based on chromium oxide and/or aluminum oxide. Often as a source of a reactive gas is used mainly clean, not containing gaseous diluents propane. The dehydrogenation catalyst in most cases also contains no diluents.

For large-scale production would be advisable to use three shell-and-tube reactors, two of which were operated wouldn mode dehydrogenation, and the third reactor during regeneration of the catalyst.

To implement the above dehydrogenation of propane used, for example, known from the literature method BASF Linde.

Along with them use a process called active conversion with steam ("steam active reforming (STAR) process"), developed by Phillips Petroleum Co. (see, for example, U.S. patent US-A 4902849, US-A 4996387 and US-A 5389342). As a dehydrogenation catalyst in this case is preferably used containing promoters platinum on zinc (magnesium) spinels as a carrier (see, for example, U.S. patent US-A 5073662). In contrast to the way BASF Linde propane, daydreamy according to the STAR process, dilute with water vapor. A typical molar ratio of water vapor : propane ranges from 4:1 to 6:1. Working pressure is often in the range of 3 to 8 MPa, a reaction temperature, it is advisable to maintain in the range from 480 to 620°C. a Typical load total reaction mixture to the catalyst is from 0.5 to 10 hours.^-1.

The propane dehydrogenation can be carried out in a reactor with a moving bed of catalyst. The catalyst may be placed, for example, in a reactor with radial flow of the gas stream, in which the catalyst slowly moves from the top down, while the mixture of reaction gases is moved in the radial direction. A similar principle is used, for example, for the dehydrogenation of the so-called method UOP-Oleflex. Because the reactor used for carrying out the method, work in quasiadiabatic mode, suitable operation of several series-connected reactors (in the typical case, the x count reaches four). This makes it possible to avoid too much temperature difference between the mixture of the reaction gases at the inlet of the reactor and the exit (adiabatic mode dehydrogenation original mix reaction gas acts as a coolant, and its ability to retain heat depends on the reaction temperature and to achieve a desired degree of conversion.

The layer of catalyst leaving the reactor is passed to the regeneration and subsequent reuse. For the implementation of this method can be used, for example, the dehydrogenation catalyst with a spherical shape of the particles, mainly consisting of platinum deposited on the surface of all particles of aluminum oxide used as the carrier. In accordance with the method UOP to fed to the dehydrogenation of propane to add hydrogen to prevent premature aging of the catalyst. In a typical case, the operating pressure is from 2 to 5 bar. The ratio of hydrogen : propane, it is advisable to maintain in the range of from 0.1:1 to 1:1. The reaction temperature is preferably from 550 to 650°C, contact time of the catalyst with the reaction gas mixture is from 2 to 6 h^-1.

In the methods of dehydrogenation, requires the use of a fixed catalyst layer, the catalyst particles can have expericence, and cylindrical (hollow or solid cylinders).

According to another variant, described in the Proceedings De Witt, Petrochem. Review, Houston, Texas, 1992 a, N1, heterogeneous catalytic propane dehydrogenation can be carried out in the fluidized bed without dilution of propane.

Thus, it is expedient to use two fluidized bed, in one of which the catalyst typically is subjected to regeneration. As an active mix use chromium oxide on the media, representing the aluminum oxide. In a typical case, the operating pressure is from 1 to 1.5 ATM, and the temperature of the dehydrogenation typically is in the range from 550 to 600°C. Necessary to carry out the dehydrogenation heat supplied to the reaction system due to pre-heat the catalyst to the reaction temperature. Working pressure is from 1 to 2 ATM, the typical reaction temperature from 550 to 600°C. Considered the way dehydrogenation known from the literature as a way Snamprogetti-Yarsintez.

The alternative described above can serve as a way of heterogeneous catalytic dehydrogenation of propane, implemented with virtually complete exclusion of oxygen, developed by ABB Lummus Crest (see Proceedings De Witt, Petrochem. Review, Houston, Texas, 1992, P1).

A common feature is still known methods heterogeneous catalytics the CSOs dehydrogenation of propane, implemented with virtually complete exclusion of oxygen, is that the degree of conversion of propane for a single pass through the reactor exceeds 30 mol.%, as a rule, less than or equal to 60 mol.%. It is possible to achieve advantages by limiting the degree of transformation of an interval greater than or equal to 5 mol.%, but less than or equal to 30 mol.% or less than or equal to 25 mol.%. This means that the propane dehydrogenation can be implemented to the extent of its transformation for a single passage constituting from 10 to 20 mol.%. This leads, in particular, to the fact that neprevyshenie propane at a later stage (C) is diluted with molecular oxygen, which reduces the output of such by-products as propionic aldehyde and/or propionic acid.

To implement the above degrees of conversion of propane is preferred dehydrogenation at an operating pressure of from 0.3 to 3 ATM. Along with this favorable role played by the dilution subjected to dehydrogenation of propane with water vapor. Due to the high heat capacity of water, on the one hand, it is possible to partially compensate for the endothermic effect dehydrogenation, and, on the other hand, the dilution water vapor provides a reduction in the partial pressure of the dehydrogenation product, which is a positive effect on the equilibrium position. In addition, as reported above, use isawanya water vapor has a beneficial effect on the durability of the catalyst. Optionally, as an additional component in the original mixture can be added molecular hydrogen, and its molar ratio to the propane, as a rule, less than or equal to 5:1. Given the relatively low degree of conversion of propane, the molar ratio of water vapor : propane can be from greater than or equal to 0:1 to 30:1, suitable from 0.1:1 to 2:1, preferably from 0.5:1 to 1:1. A favorable feature of the method of dehydrogenation of propane with a low degree of its transformation is that once passing the reaction gas through the reactor consumes a relatively small amount of heat and to achieve the transformation of sufficient relatively low reaction temperature.

It may be appropriate implementation dehydrogenation of propane to a relatively low extent of its transformation into a quasi-adiabatic conditions. This means that the source of the gaseous reaction mixture is heated, typically to a temperature of from 500 to 700°With (for example, by direct fire heating the walls of the reactor or from 550 to 650°C. normally enough only adiabatic passing the source gas through the catalyst bed to achieve the desired degree of conversion, the temperature of the reaction mixture is reduced by 30-200°With (depending on the degree of conversion. The implementation of the dehydrogenation in the adiabatic regime also promotes the use of coolant water vapor. Low temperature reactions can extend the service life used for dehydrogenation catalyst layer.

The propane dehydrogenation with comparatively low degree of conversion regardless of the mode (adiabatic or isothermal) in principle can be implemented in the reactor with stationary and moving or fluidized bed.

It is noteworthy that for the dehydrogenation, in particular, in the adiabatic regime enough to use as a reactor with a fixed catalyst bed shaft furnace, and the reaction mixture is passed in an axial and/or radial directions.

In the most simple case we are talking about a separate, closed reaction volume, for example about tank whose inside diameter is from 0.1 to 10 m, it is also possible from 0.5 to 5 m, and the fixed catalyst bed is placed on the support device, for example the grate and hot, containing propane, the reaction gas is passed in an axial direction via filled with a catalyst, thermally insulated reaction volume that was possible operation of the reactor in the adiabatic regime. Ka is Aligator may be in the form of spheres, rings or rods. Because in this case it is extremely economical to use the reaction device, the catalyst particles can have any geometrical parameters, is able to provide the low pressure loss of the reaction gas. First of all use catalysts with geometric parameters that allow you to create a large hollow space or structure, for example, such cell. For the implementation of the radial stream containing propane reaction gas to the reactor may, for example, consist of two cylindrical, coaxially located relative to each other, placed in the drum grate, and the catalyst is loaded into the annular gap between them. To effect the dehydrogenation in the adiabatic regime the metal shell should be provided with a thermal insulation.

As catalysts for the dehydrogenation of propane to the relatively limited depth of its transformation, achieved in a single pass through the reactor, is suitable, in particular, the catalysts described in the German patent application DE-A 19937107 primarily described in the German patent application DE-A 19937107, primarily given in the respective examples.

After extended use, these catalysts can be regenerated in a simple manner according to the which in the first stage, performed at a temperature of from 300 to 600°With, in particular from 400 to 500°through the catalyst bed is passed diluted with nitrogen air. Load regenerating gas mixture in the catalyst may be, for example, from 50 to 10000 h^-1and the oxygen content of from 0.5 to 20 vol.%.

The next stage of the regeneration is carried out in similar conditions, but as a regenerating gas used air. From a technological point of view it is advisable before regeneration purging the catalyst with an inert gas such as nitrogen.

In conclusion, as a rule, it is recommended to make the final regeneration of the catalyst, passing through it pure molecular hydrogen or diluted with an inert gas molecular hydrogen (hydrogen content must be greater than or equal to 1 vol.%), while the rest of the regeneration conditions remain unchanged.

Dehydrogenation of propane to a relatively small degree of transformation (less than or equal to 30 mol.%) in all cases, can be done in the same loadings on the catalyst (concerning both the General reaction gas, and contained propane), as in the variants with high conversion (>30 mol.%). Load the reaction gas in the catalyst may be, for example, from 100 to 10000 h^-1in particular from 100 to 3000 h^-1then is there is often ranges from 100 to 2000 h ^-1.

Especially attractive is the process of dehydrogenation of propane to a relatively small degree of transformation in Cordova reactor.

In link reactor is placed a few have consistently preferably in radial or axial direction of the layers of the dehydrogenation catalyst, the amount of which can be from 1 to 20, suitable from 2 to 8, and from 3 to 6. From a technological point of view in chordates reactors it is advisable to use a fixed catalyst layers.

In the simplest case, the fixed layers of the catalyst located in a shaft kiln axially or in the annular gaps between the coaxially inserted into each other cylindrical grate bars. Alternatively, according to which the catalyst is placed in the segments of the annular gap located on different levels, and served in the radial direction of the gas flows from one segment to another, below or above the first.

It is appropriate intermediate heating a mixture of the reaction gases in Cordova reactor, for which on the way from one catalyst layer to the next, this mixture is passed through, for example, heated by hot gases ribbed heat exchanger or through a pipe heated by the hot reaction gases.

If hardonyear operated in an adiabatic mode, for the desired degree of conversion of propane (less than or equal to 30 vol.%), carried out, in particular, with the use of the catalysts described in the German patent application DE-A 19937107, in particular, in the versions presented in the respective examples, simply enter the link in the reactor is pre-heated to between 450 and 550°With a mixture of reaction gas and to maintain inside this temperature. Thus, the propane dehydrogenation can be carried out at extremely low temperatures, which ensures an especially long service life of the fixed catalyst between two sequentially performed by the cycles of regeneration.

More effective is the intermediate heating of the reaction gases (autothermal method of heating). According to this method to the mixture of the reaction gases leaving the first catalyst layer and/or passing between subsequent layers, add a small amount of molecular oxygen. Depending on the features used for dehydrogenation catalyst that leads to a limited combustion contained in the mixture of the reaction gases, and, if necessary, already formed on the catalyst surface deposits of coal or prepodobnykh compounds and/or hydrogen generated in the process of digid the financing of propane and/or introduced into the mixture of the reaction gases. From a technological point of view, it may be appropriate introduction to link the reactor layers of additional catalyst specific (selective) combustion of hydrogen and/or hydrocarbons). These additional catalysts reported, for example, in U.S. patent US-A 4788371, US-A 4886928, US-A 5430209, US-A 5530171, US-A 5527979 and US-A 5563314. For example, their educated layers may alternate in Cordova reactor with catalyst dehydrogenation. The heat generated through the use of quasiattractor method allows for heterogeneous catalytic dehydrogenation of propane in virtually isothermally. With the increase in residence time of the reaction gas in the catalyst bed becomes possible dehydrogenation of propane with declining or mostly constant temperature, which allows to provide an especially long period of operation of the catalyst between two sequentially performed by the cycles of regeneration.

The above recharge of oxygen should be, as a rule, so that the oxygen content in the reaction gas mixture was varied from 0.5 to 10 vol.% in relation to entering into the composition of this mixture of propane and propene. The oxygen source can be either pure molecular oxygen or oxygen diluted netname gases, for example, carbon monoxide, carbon dioxide, nitrogen, noble gases, and, in particular, air. From the combustion gases, as a rule, play the role of additional diluents, thanks to which they contribute to the flow of heterogeneous catalytic dehydrogenation of propane.

A more complete approximation to the isothermal regime in the heterogeneous catalytic dehydrogenation of propane can be achieved by placing a link in the reactor, namely in the free space between the layers of catalyst, closed, if necessary, pre-evacuated, and possibly nemacheilinae internal elements, such as pipes. Such elements can be placed directly into the catalyst bed. They contain suitably selected solid or liquid substances which at a certain temperature evaporate or melt, which is spent on the corresponding thermal energy, and where the temperature is below the point of evaporation or melting is accompanied by heat condensation of these substances.

Another possibility of heating the mixture of reaction gases is the burning of a certain part of the contained propane and/or hydrogen by adding the necessary amount of molecular oxygen (for example, by simple pereus the a and/or passing the reaction gases through a specific action catalysts combustion and released from the combustion of thermal energy for heating the gas to the desired temperature. Combustion products, in particular carbon dioxide, water and nitrogen, if necessary, supplied together with used for combustion with molecular oxygen, play the role of a preferably inert gaseous diluents.

According to the invention neprevyshenie at the stage (C) propane (if necessary, together with propene) after selection of the target products (acrolein and/or acrylic acid) may be subjected to dehydrogenation carried out as described above, and the resulting mixture of gaseous products, is processed at stage (a).

In General neprevyshenie when the dehydrogenation of propane is playing at the stage (C) the role of gaseous diluent.

In addition, if, in particular, carry out the dehydrogenation of propane, there is a possibility of adding to the fed to stage (C) gas In pure propane and/or propene.

If stage (C) is the conversion of propene to acrylic acid, the corresponding abgas along with neprevzaidennymi in the oxidation process components, namely propane, nitrogen and residual oxygen, contains also able to oxidize side components, such as carbon monoxide, formic acid, formaldehyde, acetic acid, and small quantities of acrylic acid. In accordance with particularly preferably the m variant of the invention, these by-products before the propane dehydrogenation may be subjected to catalytic oxidation of residual oxygen and if necessary, an additional amount of molecular oxygen to heat the gas supplied to the dehydrogenation. Oxidation by-products can be carried out in the presence of a catalyst combustion chamber, in particular palladium, deposited on a substrate made of alumina, for example catalyst RO-20/13 or RO-20/25 (BASF).

Preferred embodiments of the invention are represented in figure 1-7, further explain the invention without limiting its scope.

Figure 1-5 shows schematically the preferred ways, and for simplicity are not shown, all input and exhaust flows. Figure 1 shows the following stages of the technological process: 1 - the absorption and desorption, 2 - oxidation of propene to acrolein and/or acrylic acid and 3 - selection. In stage 1 of a mixture containing propane, propene, hydrogen, carbon monoxide, carbon dioxide, and possibly nitrogen and other hydrocarbons by absorption corresponding absorbent produce propane and propene, which are then desorbed by steaming the air. Thanks to the implementation of this stage remove the hydrogen, carbon monoxide, other hydrocarbons and nitrogen. Then the gas stream containing propene and, if necessary, propane, direct to the stage of oxidation of 2, where propene oxidizes to acrolein and/or acrylic acid. Obtained in stage 2 etc the product is sent for processing at stage 3, where the produce acrolein or acrylic acid as the target product. Neprevyshenie propene and propane, carbon oxide and, if necessary, residual nitrogen and oxygen are sent to the stage of absorption and desorption 1.

The figures shown in the other drawings indicate the same as in figure 1.

Unlike figure 1 figure 2 shows phase dehydrogenation of propane 4, which can be carried out with oxygen or without it. The gas mixture obtained in the dehydrogenation of propane and containing, along with propane and propene hydrogen, oxides of carbon and possible residual amounts of nitrogen and hydrocarbons is passed to the stage of absorption/desorption 1.

In contrast to figure 1, figure 3 instead of the phase oxidation of propene 2 presents stage 22, which carry out the oxidation of propane to acrolein and/or acrylic acid.

According to figure 4 the products selected in stage 3, direct to the stage dehydrogenation of propane 4, which is carried out with oxygen or without it, and formed at this stage, the gas mixture is fed to the stage of absorption/desorption 1.

Figure 5 shows another preferred embodiment of the invention, according to which after the stage of absorption and desorption 1 carry out the dehydrogenation of propane 5 with oxygen.

Figure 6 and 7 show other predpochtitel the major ways. The method depicted in Fig.6, with the technological scheme presented on figure 4. As can be seen from the figure 6 circuit, to effect the dehydrogenation of propane (stage 4) use the three reactors, the first of which before the propane dehydrogenation (PDH) carry out the oxidation of carbon monoxide (CO-NV), and in the next two reactors before the propane dehydrogenation (PDH) dorogaya hydrogen (H₂-NV). Due to the oxidation of these products are necessary for the dehydrogenation of propane heat. The number of reactors designed for propane dehydrogenation, limit three. Propane serves on stage dehydrogenation of 4 pipeline (30), and pipe (6) can enter the air. The resulting dehydrogenation of propane gas mixture is fed through the heat exchanger W and compressor V to an absorption column K1 and desorption column K2. The absorbent after desorption in the column K2 is returned to the absorption column K1. Not absorbed by the absorbent gas removed from the process in the form of abhasa (33), if necessary, previously passed through the device for reuse that is, the Gas stream containing the selected propane and/or propene, comes to the stage of oxidation of 2, which consists of four reactors. The number intended for oxidation reactors, however, are not limited the tsya four. Then in stage 3 produce acrolein and/or acrylic acid as the target product and divert them through the pipeline (31). Neprevyshenie propane and/or propene as recirculation gas return pipeline (32) on stage dehydrogenation of 4 together with other, not selected by absorption of gaseous components.

As shown in Fig.7, the recirculation gas (1)coming from the stage selection 3 at a temperature of from 10 to 90°and a pressure of from 0.8 to 5 bar, which can be subjected to additional compression, for example, by a compressor VO to a pressure of from 2 to 10 bar, heated to a temperature of from 100 to 650°C, passing through the heat exchanger W1, in which countercurrent serves the reaction gas (2), the resulting propane dehydrogenation (PDH) in stage 4. Here and further description is shown in Fig.7. schematic of the pressure values are specified in absolute units.

Compression of gas mixtures can be performed by any suitable for this purpose are known in the art compressors, the design of which will be described in more detail below.

The recirculating gas stream (1) contains from 40 to 80 vol.% nitrogen, 1 to 5% vol. carbon dioxide from 0.1 to 2% vol. carbon monoxide, from 2 to 5 vol.% oxygen, from 0.5 to 25 vol.% moisture, other by-products of oxidation, from 5 to 40 vol.% C is Avramenko propane and 0.1 to 3% vol. neprevyshenie of propene. Before or after heating this gas stream is mixed with fresh propane (3) and preferably water and steam (4)before submitting it to the stage dehydrogenation of propane 4. As a source of fresh propane fit any gases or liquids containing propane. The preferred source of fresh propane is, however, technical propane (containing the main product of more than 90%, in particular more than 95%, particularly preferably more than 98% with a limited content of C₄ ⁺or pure propane (containing the main product of more than 99%). The molar ratio of water or steam to propane in the gas stream is from 0.05:1 to 5:1, preferably from 0.1:1 to 2:1. Favorable could be the role of supplementation in the composition of this gas stream of hydrogen (5), air (6) or oxygen-containing gas, and other components are transformed in the process of dehydrogenation of propane with an exothermic effect, for example, carbon monoxide or mixtures thereof, with hydrogen, in particular the synthesis gas. The purity of these gases there are no claims. Esotericist oxidation of combustible components in the process of dehydrogenation of propane allows you to compensate for the endothermic effect that accompanies dehydration, so it may be necessary conclusions from the outside whether the ü limited amount of thermal energy, and in the most optimal situation, it may not be necessary at all.

The pressure in the dehydrogenation of propane is from 0.3 to 10 bar, preferably from 1 to 5 bar, a temperature of from 350 to 700°C, preferably from 400 to 600°C. For dehydrogenation of propane can be used in reactors of any known specialists constructive type, such as devices with the axial direction of the gas flow, in particular chord reactors, as well as devices with multiple, arranged in the form of a hollow cylinder catalyst and a radial direction of the gas flow or more separate devices, for example, having the form of columns, cakes (Tortenform) or spheres. The number used for propane dehydrogenation reactors is not limited to three. Several separate devices are used because it provides the simplicity of interim submission of additional gases. In addition, this allows the process to be handled in a particular reactor catalyst, such as regeneration, regardless of what happens in other reactors. For this example, the reactor to be regenerated catalyst isolated from the main gas flow through the respective valve bodies, such as dampers, valves or valves located on connect the affected individual reactors, pipelines, pass through a layer of catalyst necessary for its regeneration gases, for example nitrogen, hydrogen, oxygen-depleted air or enriched air or oxygen gases and remove formed on the catalyst surface sediments. In other reactors, the total number of which can range from 1 to 20, preferably from 2 to 5, continue to serve the main gas stream, receiving the target product propene.

Intended for propane dehydrogenation reactors the catalyst layers can be stacked on the lattice, granular mass of inert material or other well-known specialists support device. The catalyst particles can have any shape without any restrictions, including, for example, crushed particles, spheres, short rods, rings, cylinders, and structured nozzles or monoliths. Preferred are the geometrical parameters, which corresponds to the minimum loss of pressure.

For uniform distribution applied to the catalyst gas may be used known in the art devices, such as sieve trays, annular or tubular gas distributors, and random backfill or structured packing, for example static mixers.

In reactors designed for propane dehydrogenation, can be the ü placed several layers of catalyst, each of which performs a specific function. If you use a few of these layers, the front layer of the catalyst dehydrogenation is preferably placed one or more layers consisting of catalysts, under the influence that may lead to the oxidation of substances other than propane or propene, for example hydrogen (catalyst H₂-NV), carbon monoxide (CO catalyst-NV) and/or other, are able to oxidize a component. However, if these functions are performed by the catalyst in the dehydrogenation of propane or loss of propane as a result of its oxidation are economically feasible, should, if possible, to abandon the use of additional catalysts.

The specific productivity of the catalysts for the dehydrogenation of propane can be from 100 to 20000 normal liters (nl) propane per liter of catalyst per hour. Preferably this ratio is in the range from 500 to 10000, more preferably 1000 to 10000. The specific productivity of the catalysts, mainly oxidizing, such as carbon monoxide or hydrogen with simultaneous slight oxidation of propane or propene, is usually in the range from 5000 to 30000 IO per liter of catalyst per hour.

The degree of conversion of propane when the dehydrogenation is from 10 to 60%, preferably from 20 to 50%, in particular from 88%to 9%. It is preferable to complete the transformation introduced into the reactor in gaseous carbon monoxide, hydrogen or other combustible gases. The degree of conversion of the hydrogen formed during the dehydrogenation of propane, depending on the degree of conversion of the propane is from 1 to 99%, frequently from 10 to 80%, in particular from 30 to 70%.

The reaction gas (2)resulting from the dehydrogenation of propane contains from 20 to 60 vol.% nitrogen, 1 to 5% vol. carbon dioxide from 0.5 to 45% vol. water, from 5 to 45 vol.% propane, from 1 to 20 vol.% of propene from 1 to 20 vol.% hydrogen and other by-products such as ethane, Aten, methane and C₄ ⁺.

Formed during propane dehydrogenation reaction gas (2) has a temperature of from 400 to 650°S, more preferably from 450 to 600°and pressure from 0.3 to 10 bar, more preferably from 1 to 5 bar. Gas (2) through heat exchange in counter-current heat exchanger W1 with the recirculation gas (1) is cooled to a temperature at least 5°better, at least 50°and preferably at least 100°higher than the temperature of the recirculation gas (1) at the entrance to the heat exchanger. Then the gas flow (3) depending on the temperature at the outlet of the counterflow heat exchanger W1 undergoes additional cooling 10-60°carried out by the mu in one or several stages. When using multiple stages depending on the temperature level of the cooling in the heat exchanger W2 may occur due to steam generation or supply of the cooling air and the cooling in the heat exchanger W3 due to the supply of cooling air, water or brine. However, depending on the pressure, temperature and moisture content of gas streams (3)-(5) involves condensation of moisture, which is separated from the gas stream (5) in the separator A1. The separator may be any known in the art and are suitable for gas separation design.

Then cooled and, if necessary, partially dehydrated gas stream (6) is subjected to compression, and the compression ratio is in the range bounded by the magnitude of the gas pressure at the outlet of the separator A1, on the one hand, and 50 bars. Compression can be performed by single-stage or multistage compressor with intermediate cooling or without him. The compressor V1 can be any known in the art design. For example, you can use reciprocating, rotary, screw, membrane, plate, turbine and centrifugal compressors, and rotary and centrifugal blowers, and are preferred turbine and centrifugal compressors. Criteria when choosing the type whom the spring are the compression ratio and the number of exposed gas compression. When multistage compression with intermediate cooling results in condensation of moisture and, if necessary, others are able to condense components that can be separated from the gas stream, as described above, after intermediate cooling or during its implementation, before directing the gas flow to the next stage of compression. Compressed to the desired final pressure of the gas stream (7) can be subjected to one - or multi-stage cooling, as described above, and the moisture and, if necessary, more can condense components can be separated from gas streams(7)-(9).

The drive of the compressor V1 can use the electric motors, and steam or gas turbines. The choice of the type of actuator depends on the production infrastructure, but more often as a drive using steam turbines that have the highest efficiency.

If you want to increase the ratio of water to supplied to the dehydrogenation of propane, the condensed set of threads, such as thread (11) (after increasing pressure) and flow (12) return to the stage dehydrogenation of propane, and the remainder slugout and, if necessary, burn. Condensate flow (13) before recycling or locking evaporated or subjected to any other treatment, e.g. the measures cleanup.

The gas stream (10) is sent to an absorption column K1, where the contact with him absorbent absorbs₃-hydrocarbons (propane and/or propene) and, if necessary, other components. As the absorbent may use any known specialists substances, and are preferred above absorbents. Preferred is a multi-stage countercurrent contacting of the gas stream (10) with absorbent material. Temperature absorption can range from 10 to 150°better from 20 to 80°C, preferably from 30 to 60°and a pressure from 1 to 50 bar, better from 3 to 30 bar, preferably from 5 to 20 bar.

Suitable are known in the art of constructive options absorber K1, for example, described in "Thermische Trennver-fahren", Klaus Sattel, VCH, 1988, (ISBN 3-527-28636-5). Preferred are columns with internal elements are also known in the art structural design, for example, absorbers with sieve plates, plates with dual stream dome, tunnel, lattice or the valve absorbers with messy filling, for example, Raschig rings, rings PAL, seat type Intalox, saddles Burleigh, seat type Super or Torus, the inner nozzle bodies or rings of metal fabric, as well as absorbers with structured nozzle (for example, type Sulzer-Kerapak, Sulzer-Packung BX Ilisu or, for example, nozzles firm Montz and other manufacturers). Particularly suitable is the nozzle Ralu-Pak 250. YC company Raschig. However, preferred are built-in items that allow you to operate the absorber with a high flow rate (high density irrigation), for example, unstructured backfill or structured packing. In a preferred embodiment, the density of irrigation should be more than 50 m³better yet, more than 80 m³liquid per square meter of the free surface per hour. Inline elements can be made of metal and ceramics, and polymers or combinations of several materials. The basic principle in the selection of material suitable for use as backfill or nozzle, is a good wetting of the absorbent material.

The ratio between the streams fed to the absorber absorbent (24) and gas (10) is determined on the basis of the relevant requirements of thermodynamics. It depends on the number of stages of separation, temperature, pressure, the absorption ability of the absorbent material and the desired level of separation of absorbable product. This ratio is usually from 1:1 to 50:1, in particular from 1:1 to 30:1, preferably from 1:1 to 20:1 (kg/kg) when the number of theoretical stages from 1 to 40, in particular from 2 to 30, preferably from 5 to are the number of steps can be calculated, using the specialized literature, for example "Thermische Trennverfahren", Klaus Sattel, VCH, 1988 (ISBN 3-527-28636-5).

So that, if necessary, to reduce the loss of the absorbent is released from propane and/or propene gas stream (14) can be directed to the stage of hardening. The relevant principle is explained in more detail in the following description, stage desorption.

After quenching the gas stream (14) can be subjected to decompression, which can be performed by single or multi - stage throttling without energy recovery or by single or multi - stage regeneration of mechanical energy in a gas turbine T1. In the latter case, the gas stream (14) before entering the turbine is sometimes necessary to heat. Heating may be carried out directly by catalyzed or acatalasemia oxidation contained in the composition of this gas stream or input from the outside of combustible and oxidizing components or by indirect heat by means of steam or outdoor fire heating. The resulting decompression of mechanical energy can be used to actuate the actuator of one of the compressors, preferably compressor V1 as a secondary or primary source of energy and/or to generate electrical current.

According to the t degree of purity of the resulting decompression stream abhasa (15) can be directed to the catalyzed or acatalasemia burning or discharged into the atmosphere.

The flow of the absorbent (16), mainly consisting of propane (from 2 to 30 vol.%) and/or propene from 2 to 30 vol.%) and, if necessary, contain other components (e.g., carbon dioxide,₂ ^-With₄ ⁺, water), if necessary, is subjected to decompression, and then sent to the desorption column K2. Decompression of the adsorbent can be carried out without regeneration mechanical energy by one - or multi-stage throttling, as well as regeneration of mechanical energy, for example, in the turbine or rotating in the opposite direction of the centrifugal pump. You may need heat absorbent (16) before desorption, which is preferably carried out by heat exchange in counter-current heat exchanger W6 flow (17). Do not eliminate the need for additional heat flow (16)extending from the heat exchanger.

Desorption of propane and/or propene in desorber K2 can be implemented by distillation (single simple evaporation or steam, and desorption contributes to reduced pressure of 0.1-10 bar, in particular 1-5 bar, preferably 1.5 to 3 bar.

When it comes to desorption by distillation, it can be carried out in any known in the art. A particularly simple form of the desorption of the two is as simple single-stage (instantaneous) evaporation of the absorbent in the designated device. Before performing this operation it is advisable to heat the stream (16) to a temperature of from 20 to 300°With, in particular from 40 to 200°C, preferably from 50 to 150°C. the Corresponding device must be designed to ensure proper thermodynamic conditions for the allocation of propane or propene from the absorbent and appropriate hydrodynamic conditions for the separation of gas from liquid. In particular, the apparatus may take the form of a cylinder or sphere, as well as other well-known specialists constructive form. If he has a cylindrical shape, it is possible to have both in vertical and in the horizontal plane. The inlet line, usually located between the fittings intended for removal, respectively, the gas and the liquid. In the simplest case, the device does not contain any additional built-in items. To create the optimum thermodynamic conditions desorption inside the device can be mounted inline elements, typically used in the technique of distillation, absorption, and steaming, in particular the elements listed above in the description of absorption. For optimal hydrodynamic conditions of gas separation from the liquid inside the device can be integrated with relevant, well-known specialists of additional built-in items, such as wire cloth, is ergorace, changing the direction of motion, or similar items. In addition, the apparatus can be enabled devices, ensuring the supply of energy, such as heating coils or screens.

If in this case there is air or similar otvarivaya environment, such as water vapor, nitrogen, fresh propane or another, required for use in the process gas, it is advisable to use them for keeping up of process of the instant evaporation of the absorbent material.

This special form of the process is multi-step Stripping of volatile components (propane and/or propene) through the source gas stream (25)intended for oxidation (in this case, as with the single-stage Stripping simultaneous Stripping of the thread (10) any additional absorption components, as well as other substances which could be formed due to their volatility). In the simplest case, the source gas stream (25) is the air required for oxidation of propane to acrolein or acrylic acid. This compression of the air or the source of the gas stream can be carried out both before desorption, and after it. The original gas stream (25) along with air may also contain the recirculation gas from stage received the I of acrylic acid, as well as water vapor, fresh propane or other identityoverride gaseous components. Particularly favorable for the desorption process is a countercurrent or cross-current source gas flow (25) with respect to the liquid absorbent. In the case of backflow of desorber can be performed similarly to the above-described absorption column.

Cross-talk is useful if the desorption process are crossing the border region of the explosion. This situation occurs if the terms of the propensity to ignite the source of the gas stream (25) is a "lean" gas mixture, and the output of desorber containing propane and/or propene gas stream (18) is the "fat" of the gas mixture. The gas mixture is called "skinny"if it contains too little of combustible materials in order to be able to fire, and "fat", if it contains too many combustible substances to possess this ability.

When using a cross flow total gas flow serves not cube desorption columns, but in the form of separate streams enter at multiple points along it so that no one part of desorber was not present capable of ignition of the gas mixture. However desorber can be located both in vertical and in horizontal p is Ascoli.

Another possibility of solving the problem of explosion when desorption capable of ignition components included in the composition of the oxygen-containing gas flows, consists in mixing the source of the gas stream before entry into the desorption column with a substance (for example, propane, propene, methane, ethane, butane, water, and so forth)due to the presence of which is supplied to desorber gas mixture becomes "fatty". There is also the possibility to split the gas flow and enter into the cube desorption columns of the source gas containing propane or propene to ensure the lowest possible content of propane and/or propene in the stream of absorbent (17), and the source gas, the fat content of which is increased, for example, by adding propane and/or propene, to serve in that part of the desorption column, which can be formed capable of ignition of the gas mixture.

The flow of the absorbent (17) with low content of propane and/or propene possible after passing through the counterflow heat exchanger W6 and increase the pressure by means of pump P1 may be subject to additional one - or multi-stage cooling (e.g. heat exchanger W7) through line (24) is again directed to the absorber K1.

In the General case of multi-stage desorption can be performed the ri of any pressures and temperatures. Preferred, however, are lower pressure and higher temperature compared to absorption. In this case, the pressure is from 1 to 5 bar, in particular from 2 to 3 bar, temperatures from 20 to 200°With, in particular from 30 to 100°S, particularly preferably from 35 to 70°C.

The flow of the absorbent (17) to the flow of the source gas (25) must meet the requirements of thermodynamics, and it depends on the number of stages of separation, temperature, pressure, the ability of the absorbent to decarbonate absorbed substances and the required degree of separation. It usually takes from 1:1 to 50:1, in particular from 5:1 to 40:1, preferably from 10:1 to 30:1 (kg/kg) theoretical number of stages of separation from 1 to 20, in particular from 2 to 15, preferably from 3 to 10.

In the General case, the source containing propane and/or propene gas flow without additional processing may be directed to the stage of oxidation 2. However, it may be appropriate to send it before oxidation on an additional process stage, for example, to reduce losses otvarennogo absorbent. The absorbent material may be separated from the fed to the oxidation of the gas stream by any known specialists of ways, one of which is rapid cooling (quenching) of the gas stream with water. Water washing (temper is) can be produced in the upper part of the desorption column on catching the liquid in a bowl or in a separate apparatus. To enhance the effect of separation within the device for quenching can be mounted built-in items that are similar are usually used in distillation, absorption and desorption and above in the description of absorption. The same applies to a separate apparatus for hardening.

A mixture of water and absorbent, resulting from the allocation of absorbent containing propane and/or propene gas stream by washing with water (19), can be subjected to a phase separation in the device D1, and removed water from the gas stream (18) after a possible heating is directed to phase oxidation of propane (2).

Phase separation can be implemented in any well-known specialists in the form of, for example, by solvent extraction. In the most simple case of organic absorbent is separated from the used for quenching water in a horizontally or vertically mounted devices oblong form with embedded elements or without them. The ratio of the diameter of such devices to the length can be from 1:1 to 1:100, in particular from 1:1 to 1:10, preferably from 1:1 to 1:3. The apparatus may be completely filled with fluid, or there may be a gas cushion. For the best separation of the organic phase can be equipped with a dome, which can be draining absorbent. Better sharing what I can to promote the use of well-known specialists of built elements, for example, wire fabrics, candles winding (Wickelkerzen) or partitions, changing the direction of movement. Phase separation can also be used in rotating machines such as centrifuges.

The resulting phase separation of the absorbent material (20) may be returned in desorber. Quenching water before returning to the quenching apparatus, if necessary, can be chilled or heated in the heat exchanger W9. Large quantities of quenching water is more preferable to pump the appropriate pump P2. The density of irrigation in the quenching apparatus exceeds 30 m³in particular 50 m³preferably 80 m³but is less than 1000 m³in particular less than 500 m³preferably less than 300 m³water per square meter of free cross-section of a quenching apparatus in an hour.

The loss of water during hardening can be compensated by feed water condensate (21) or containing acid water (22)formed at the stage of obtaining acrylic acid. To avoid overflow, part of the circulating quench water slugout in the form of a cleansing stream (23) and is directed to the installation for incineration or eliminate any other way (for example, sent to effluent treatment plant).

If applied to stage 2 oxidation gas stream (18) has a temperature of no is e 90° C, in particular below 70°and a pressure from 1 to 3 bar, it is advisable to add water, which is carried out by mixing with water vapor or saturated with water in the saturator known in the art of constructive type.

The gas stream (18) contains from 30 to 70 vol.% nitrogen, from 5 to 20 vol.% oxygen, from 2 to 15 vol.% of propene, from 2 to 40 vol.% propane, from 0.5 to 25 vol.% water and other components, in particular carbon dioxide, methane, ethane, Aten, C₄ ⁺. It can be directed to the stage of oxidation of 2, implemented as described above or known from the patent literature methods. Oxidation of propene or acrolein can be carried out in the reactors according to the prior art with salt bath, for example, manufacturing shipyard of Deggendorfer or in reactors of other types. Between the first (getting acrolein) and second (obtaining acrylic acid) levels of oxidation can be carried out supplementary feeding reaction gas air or water vapor. The high content₃-hydrocarbons in the feed to the stage of oxidation of 2 gas flow (18) in any case contributes to the heat of reaction from the reaction volume. Fit is the submission of propene in the amount of from 50 to 350, in particular from 90 to 300, preferably from 100 to 250, IO per liter of catalyst per hour.

The selection at stage 3 and iloveu acid from the reaction gas (26), from the stage of oxidation of 2, can be carried out, as described above, for example, by using high-boiling solvents, in particular a mixture of defile with dimethylphthalate, and through the absorption of water or fractionated condensation.

Acrylic acid can be purified from impurities by Stripping and distillation, azeotropic distillation or by crystallization.

The process is carried out in accordance with is depicted in Fig.7. the technological scheme, suitable for retrofitting any existing installations, designed to get acrolein and/or acrylic acid, and combining with the new settings for the synthesis of acrylic acid.

Unexpectedly, it was found that, as a rule, the expected residues of the absorbent in the composition of the gas does not lead to any negative effects on the oxidation process and the properties used for its implementation catalyst. Not seen any problems caused, if necessary, taking place on the stage of oxidation of propane and/or propene formation of any oxidation products of the absorbent. If you still have encountered any problems associated with the presence of residual absorbent, which can usually be avoided by using absorbents such as high-boiling hydrocarbons, in particular Parati is s, such problems can be solved through the use of water quenching or adsorption.

Thus, it was unexpectedly found that in the method according to the invention can be used absorption. In contrast to adsorption, used in accordance with Japanese patent application JP-A-1036311, absorption of propane and/or propene according to the present invention provides a much easier and cost-effective management.

In addition, an advantage of the present invention is that installation where as the original product to obtain acrolein and/or acrylic acid is used propene, can be a convenient way converted for use as a feedstock cheaper propane.

The invention is illustrated by the following example relating to a preferred variant of the method according to the invention.

Example

Acrylic acid is obtained by the method schematically depicted in Fig.7, we use the same numerical designation as in Fig.7.

2090 nl/hour gas recirculation (1) after process stage 3 with a temperature of 30°and a pressure of 1.2 bar, serves on the compressor VO, where it is subjected to compression to 2.0 bar, and then in a counter-current heat exchanger W1, in which it is heated to a temperature of 450°Be by heat exchange with the reaction gas (2), coming from the stage dehydrogenation of propane. In this case, and in the following description, the example specifies the absolute value of the pressure in bars.

The recirculation gas (1) contains 60,3% vol. nitrogen, 1,2.% dioxide of carbon, 0,5% vol. carbon monoxide, 3,4% vol. oxygen, 1,9% vol. water, 32,2% vol. propane and 0.4 vol.% of propene, as well as by-products of oxidation. Before entering the heat exchanger recirculation gas is mixed with fresh propane (3)supplied in the amount of 170 nl/hour, and water vapor (4). As a fresh propane use technical propane content of the main product of more than 98% and C₄ ⁺100 million^-1The molar ratio of water vapor to the propane in the feed to the dehydrogenation gas flow is 0.5:1.

The gas mixture is introduced into the first of four reactors, the internal diameter of which is 50 mm reactor Design allows them to operate in autothermal mode. Each reactor contains a catalyst bed height of 110 mm, the Catalyst is a short rods with a diameter of 3 mm and a height of 5 mm

The degree of conversion of propane in the four reactors is 20% with a selectivity of formation of propene 92%.

Effluent from the dehydrogenation reactor gas (2) contains 44,9% vol. nitrogen, 2,7% vol. carbon dioxide was 16.9% vol. water 24,0% vol. propane, 5,8 about the.% of propene, 5,5% vol. hydrogen, and a small amount of by-products, in particular ethane, Athena, methane and C₄+.

The reaction gas (2) after dehydrogenation temperature 520°and a pressure of 1.5 bar is cooled to 30°C. the Cooling gas is accompanied by condensation of about 350 g/h of water (11).

The cooled gas stream (6) subjected to single-stage compression piston compressor to 7.5 bar, and then again cooled to 30°Sobratysa cooling water condensate (12) combined with the condensate (11), partially evaporated and mixed with the recirculation flow (1). Another part of the condensate (21) is directed to a device for quenching, and the residue is subjected to air-locking.

2340 nl/h of a gas stream (10) is served in the cube absorption column K1 (metal casing, an inner diameter of 80 mm, length 3 m). The internal volume of the absorber 60% completed supplementary elements of the company Montz (Montz-Pak type B1).

The gas stream (10) contains 53,9% vol. nitrogen, 3,3% vol. carbon dioxide 0,4% vol. water, 28,8% vol. propane, 7,0 vol.% of propene, 6, 6 vol.% hydrogen and small amounts of other by-products, in particular ethane, Athena, methane and C₄ ⁺.

In the upper part of the absorption column K1 of desorber K2 serves 35 kg/h tetradecane (24)having a temperature of 30°and containing a small amount With₃-hydrocarbons.

Abhas (14, containing 1150 million^-1about. propane and 750 million^-1about. of propene, is passed through the supporting pressure valve to reduce the temperature and pressure relevant to atmospheric values, then burn.

The absorbent stream (16) from the cube column K1 is passed through the supporting pressure of the valve, reducing the pressure of 2.4 bar, and served in the upper part of the desorption column K2.

The dimensions of the desorption column K2 and type of fill its nozzle is similar to the absorption column K1.

In the cube desorption column serves 1310 nl/hour compressed to 2.45 bar air at a temperature of 30°C. the Column thermostatic at a temperature of 40°C.

Abgas emerging from the desorption column (2190 nl/h) and containing a 30.7% vol. propane, 7,4% vol. of propene, 12,3% vol. oxygen, 46,4% vol. nitrogen, 1,5 vol.% water, 1.6 vol.% carbon dioxide and minor amounts tetradecane, send in the quenching apparatus located in the upper part of the desorption column K2.

The absorbent from the cube desorption column K2 pump P1 fed into the heat exchanger W7 and later in the upper part of the absorption column K1.

The quenching apparatus is a metal column with an inner diameter of 80 mm, similar to the absorption column K1 contain embedded elements. Quenching with water is carried out at a temperature of 30°With consumption of irrigation water is 120 l/cha is. Taken from the cube quenching apparatus of the two-phase liquid mixture is sent to a device for the separation of the phases D1, which is located in a horizontal position the tank with a diameter of 200 mm and a length of 500 mm, the first third of the internal volume of which (in the direction of flow) filled in a special way located a thin wire cloth. The aqueous phase selected in the device D1, is pumped into the upper part of the quenching apparatus, and the selected tetradecane (the average number is about 1 g/h) is sent to the appropriate collection. Loss of water during hardening is compensated by adding water condensate (21).

Abgas of the apparatus for quenching heated to a temperature of 200°and is directed to a two-stage oxidation.

The oxidation is carried out in the modeling tubes of 4 m length with an inner diameter of 26 mm 2.7 m first modeling tube filled with a catalyst, is described in European patent application EP-A-0575879, and 3.0 m second modeling tube catalyst described in European patent application EP-A-0017000. Between the first and second stages of oxidation serves the additional air in the amount of 315 nl/hour.

Selection of acrylic acid from the reaction gas (26), obtained by oxidation, and its purification from impurities is carried out according to Heb the European patent application EP-A-0982289.

According to this method, on average, receive 440 g/h of crude acrylic acid (27) with the content of the main product over 99.5%.

1. The method of producing acrolein and/or acrylic acid from propane and/or propene, comprising the following stages:

a) selection of propane and/or propene from the containing propane and/or propene gas mixture And by their absorption by the absorbent,

b) selection of propane and/or propene from the absorbent with a receipt containing propane and/or propene gas and

(c) obtained in stage (b) gas for oxidation of propane and/or propene to acrolein and/or acrylic acid,

and between stages (b) and (C) not carry out heterogeneous catalytic dehydrogenation of propane without oxygen.

2. The method according to claim 1, characterized in that in stage (a) serves a gas mixture containing, along with propane and/or propene, at least one additional component selected from hydrogen, nitrogen or carbon oxides.

3. The method according to p. 1 or 2, characterized in that in stage (a) as an absorbent is used, at least one alkane with 8-20 carbon atoms or an alkene with 8-20 carbon atoms.

4. The method according to one of paragraphs. 1-3, characterized in that the separation of the propane and/or propene from the absorbent in stage (b) is carried out by steaming, flash evaporation and/or d is stellazio.

5. The method according to one of the preceding paragraphs, characterized in that in stage (C) carry out the oxidation of propene to acrolein and/or acrylic acid.

6. The method according to one of paragraphs. 1-4, characterized in that in stage (C) carry out the oxidation of propane to acrolein and/or acrylic acid.

7. The method according to claim 6, wherein as catalyst for the oxidation of propane at the stage (C), a mixture of metal oxides of the formula (I)

in which M¹is tellurium (Te) and/or antimony (Sb);

M²is at least one element from the group including niobium (Nb), tantalum (TA), tungsten (W), titanium (Ti), aluminum (Al), zirconium (Zr), chromium (Cr), manganese (Mn), gallium (Ga), iron (Fe), ruthenium (Ru), cobalt (Co), rhenium (Rh), Nickel (Ni), palladium (Pd), platinum (Pt), lanthanum (La), bismuth (Bi), boron (B), cesium (Cs), tin (Sn), zinc (Zn), silicon (Si) and indium (In);

b is from 0.01 to 1;

C is from 0 to 1;

d is from 0 to 1;

n is a number determined by the valency and frequency different from the oxygen elements in the formula (I).

8. The method according to one of the preceding paragraphs, characterized in that neprevyshenie after carrying out stage (C) propane and/or propene allocate at stages (a) and (b) and return to the step (C).

9. The method according to one of the previous pun is tov, characterized in that the composition is used in stage (a) of the gas mixture And is similar to the composition of the gas mixture, which is obtained by homogeneous and/or heterogeneous catalytic dehydrogenation of propane and/or propene.

10. The method according to claim 9, characterized in that the propane dehydrogenation is performed with the addition of oxygen.

11. The method according to one of the preceding paragraphs, characterized in that neprevyshenie after carrying out stage (C) propane and optionally propene direct on stage dehydrogenation of propane and the resulting mixture of products again subjected to treatment in stage (a).

12. The method according to one of the preceding paragraphs, characterized in that stage (C) is carried out directly after stage (b).

13. The method according to one of paragraphs. 1-11, characterized in that after stage (b) and before stage (C) carry out water quenching to highlight absorbent.

Priority points and features:

20.06.2000 - 7, in addition to the characteristic "M²is at least one element from the group comprising gallium (Ga), lanthanum (La), tin (Sn), zinc (Zn), silicon (Si) and indium (In)";

07.07.2000 - feature "M²is at least one element from the group comprising gallium (Ga)";

17.04.2001 - feature "M²is at least one element from a group comprising lanthanum (La), tin (Sn), zinc (Zn), silicon (Si) and indium In)".