EP2001825A1 - Method for commercially obtaining propene - Google Patents

Abstract

The invention relates to a method for commercially obtaining propene from a gas flow containing propene and at least one additional hydrocarbon. Said method comprises the following steps; (a) the gas flow is brought into contact with an adsorber containing a porous metalorganic framework material containing at least one at least bidentate organic compound which is co-ordinately bound to at least one metal ion, said adsorber being charged with propene; and (b) the propene is released from the adsorber charged with the propene. The invention further relates to the use of a porous metalorganic framework material for commercially obtaining propene from a gas flow containing propene and at least one additional hydrocarbon.

Description

Process for the technical recovery of propene

description

The present invention relates to processes for the technical recovery of propene from a propene and at least one further hydrocarbon-containing gas stream and to the use of a porous organometallic framework for propene recovery.

Propene represents an important value product, which serves as a starting material for the production of polypropene, for example.

Propene, like its homologous olefins, only occurs in very small quantities in natural gas or crude oil. Therefore, its direct extraction by isolation from natural sources is not of economic importance.

However, there are a variety of industrial processes in which initially a mixture of propane and propene arises, for example, propane, FCC or steam cracking, MTO (methanol to olefin), etc. Therefore, in all methods, the separation of the propene from the Hydrocarbon product mixture required. This also applies to the recovery of propene by olefin metathesis. If necessary, this separation must be preceded by several purification steps.

One possibility of the separation consists in a distillation, which, however, in particular due to the similar boiling points of propane and propene (according to VDI heat Atlas 5.7 K at 1 bar, 6.1 K at 5 bar) and the high purity requirements for the propene a high Required number of theoretical plates and designed accordingly consuming and expensive.

One of the distillation superior process for the separation and recovery of propene is the adsorption.

Classical adsorbents for the technical production of propene from gas mixtures which, in addition to propene, contain further hydrocarbons, in particular propane, are zeolites.

Such zeolite-based methods are described by FA Da Silva et al., Int. Closely. Chem. Res. 40 (2001), 5758-574; FA Da Silva et al., AIChE Journal 47 (2001), 341-357 and CA. Grande et al., Int. Closely. Chem. Res. 44 (2005), 8815-8829. Despite the adsorber systems known in the art, there is a need to provide improved methods with alternative adsorbents. Here, in particular, the required high temperature in the pressure swing adsorption on zeolites is a problem. In addition, it is known that in zeolites Diffusionsprob- learning can occur and they have comparatively low specific surface areas. Furthermore, with these adsorbents the polymer grade purity can be achieved only with great effort (higher productivity (mol / (H ^* m ³ )) Furthermore, there is an incentive to carry out the adsorption at as low a pressure as possible In this case, complicated compression of the propene-containing stream is eliminated, for example propane dehydrogenations are carried out in a low pressure range of between 0.1 and 5 bar.

It is therefore an object of the present invention to provide alternative adsorbents which can be used in improved processes for the technical recovery of propene.

The object is achieved by a process for the technical recovery of propene from a propene and at least one further hydrocarbon-containing gas stream, comprising the steps

(a) contacting the gas stream with an adsorbent containing a porous organometallic framework containing at least one coordinated at least one metal ion at least bidentate organic compound, wherein the adsorbent is loaded with propene, (b) releasing the propene from the laden with propene adsorbent.

It has been shown that the use of a porous organometallic framework material in a particularly efficient manner, methods for the technical recovery of propene are possible.

The proportion of propene in the gas stream can assume different values, this proportion being highly dependent on the source of the gas stream. In this case, however, the proportion of propene which is contained in the gas stream, based on the sum of the volume fractions of propene and the further hydrocarbon or the further hydrocarbons, in particular in the presence of propane, is particularly important since the separation of hydrocarbons, in particular propane and Propen represents the main problem. The separation of other constituents of the gas stream may optionally take place in an upstream step and may also be carried out by other adsorbents instead of a porous organometallic framework. Furthermore, other methods, such as distillation, can be used for this purpose. In addition to propene, the gas stream contains at least one additional hydrocarbon. Typically, several additional hydrocarbons are included in addition. Depending on the source of the gas stream, in addition to propene, the at least one further hydrocarbon may be of different nature. Likewise, its content is usually dependent on the source of the gas stream.

In particular, the at least one hydrocarbon is propane.

Further hydrocarbons may in particular be C ₁ -C ₄ -alkanes, such as methane, ethane, propane, n-butane, isobutane, C ₂ -C ₄ -alkenes, such as ethene, 1-butene, 2-butene and C ₂ -C ₄ -alkynes such as ethyne, propyne, 1-butyne, 2-butyne and allenes. In addition, higher hydrocarbons may also be present in the gas mixture.

It is preferred that the gas stream contains from 5 to 95% by volume of propene, based on the sum of the proportions by volume of propene and the further hydrocarbon or the further hydrocarbons in the gas stream.

More preferably, the proportion of propene is 10 to 95% by volume, more preferably 30 to 95% by volume, more preferably 50 to 95% by volume, even more preferably 70 to 95% by volume, in particular 90 to 95% by volume. %. It is further preferred that the absolute content of propene in the gas stream can also assume these values.

In a preferred embodiment, the gas stream is an optionally purified product stream from propene production.

In addition to propene, such product streams typically contain further homologous alkanes, in particular propane, and alkenes and also other gaseous constituents, which, however, can be removed by simple purification steps. An example of such a cleaning-removable component of a product stream from propene production is gaseous water, which can be correspondingly removed by a conventional drying agent or by condensation during compression and cooling. Another example is carbon dioxide, which can be removed by a simple gas scrubber. Further examples are ethyne and allenes, which can be selectively hydrogenated beforehand.

The optionally purified product stream from the preparation of propene may be one which consists of a cracking process (steam cracking or catalytic cracking), of a propane dehydrogenation, of a methanol (methanol). OH) / dimethyl ether based petrochemical manufacturing process or olefin conversion (metathesis or olefin cracking).

These methods are known in the art. A starting material for cracking process can be in addition to naphtha and LPG (liquid petroleum gas). LPG mainly consists of propane and butanes.

Furthermore, a starting material liquefied gas (LNG = Liquefied Natural Gas) may be, which consists essentially of ethane, LPG and light naphtha.

Finally, naphtha itself represents a possible starting material for the production of propene. Approx. 15% by weight of the naphtha is converted to propene.

Naphtha is the starting material for steam cracking. The desired target product for cracking naphtha is usually ethyne. In addition, larger amounts of C ₃ hydrocarbons arise. By varying the temperature and residence time ("cracking sharpness"), the product spectrum, ie the distribution between C ₂ , C ₃ and C ₄ olefins can be adjusted. Typical temperatures are in the range of 800 to 1000 ° C. By dilution with steam (hence "steam bracken") a favorable heat distribution in the pipe as well as by partial pressure reduction a favoring of the formation of crack products is reached. For example, a typical composition of a product stream for C ₃ separation would be 90 to 96% propene, 3 to 7% propane, up to 3% each of propadiene and propyne, and optionally minor amounts of other higher and lower hydrocarbons such as methane , Ethane, ethylene, cyclopropane, butanes, butenes and C ₅ - and C ₆ -hydrocarbons.

The second largest source of propene is catalytic cracking, which today often employs fluid catalytic cracking (FCC), which in conventional refineries aims at alkylation or condensation for fuel production. The FCC cracking uses sand-like, fine catalysts (for example aluminum silicates) which have a large surface area. The cracking to olefins occurs at temperatures between 500 and 600 ° C with a few seconds residence time. During the cracking process the catalyst coking. For regeneration, this is continuously discharged from the actual reactor and regenerated outside by burning. The energy released during burning is returned to the process. As an alternative to cracking processes, olefin conversion olefin metathesis can also be carried out for propene production. Here, ethene and 2-butene can be converted to propene.

Finally, the methanol or dimethyl ether conversion represents a more or less targeted propene production. Such reactions are also referred to as "methanol to olefins". These reactions on zeolites (ZSM-5 or SAPO) are aimed either at propene / ethene production in addition to traces of C ₅ ⁺ or propene / gasoline production. In both cases, propene must be separated from, among other things, more or less large amounts of LPG.

A particularly preferred preparation of propene for producing an optionally purified product stream is the propane dehydrogenation.

A preferred subject of the present invention is therefore that the optionally purified product stream from a cracking process, a propane dehydrogenation, an olefin metathesis or a methanol conversion for propene production, in particular from a propane dehydrogenation.

It is also possible that appropriate mixtures of such different product streams are used.

A preferred process for propane dehydrogenation comprises the steps:

A) a propane-containing feed gas stream a is provided;

B) the propane-containing feed gas stream a, optionally water vapor and optionally an oxygen-containing gas stream are fed into a dehydrogenation zone and propane is subjected to dehydrogenation to propene, wherein a product gas stream b containing propane, propene, methane, ethane, ethene, hydrogen, optionally carbon monoxide, carbon dioxide , Water vapor and

Oxygen is obtained;

C) the product gas stream b is cooled, optionally compressed and water vapor is separated by condensation, whereby a product gas stream c depleted in water vapor is obtained.

In a first process part A), a propane-containing feed gas stream a is provided. This generally contains at least 80% by volume of propane, preferably 90% by volume of propane. In addition, the propane-containing feed gas stream a generally still contains butanes (n-butane, iso-butane). Typical compositions of the propane-containing feed gas stream are disclosed in DE-A 102 46 1 19 and DE-A 102 45 585. customary The propane-containing feed gas stream a is obtained from liquid petroleum gas (LPG).

In a process part B), the propane-containing feed gas stream is fed into a hydrogenation zone and subjected to a generally catalytic dehydrogenation. In this case, propane is partially dehydrogenated to propene in a dehydrogenation reactor on a dehydrogenating catalyst. In addition, hydrogen and small quantities of methane, ethane, ethene and C ₄ ⁺ hydrocarbons (n-butane, isobutane, butenes, butadiene) are obtained. In addition, carbon oxides (CO, CO ₂ ), in particular CO ₂ , water vapor and, if appropriate, to a lesser extent inert gases in the product gas mixture of the catalytic propane dehydrogenation are generally produced. The product gas stream of the dehydrogenation generally contains water vapor which has already been added to the dehydrogenation gas mixture and / or, upon dehydrogenation in the presence of oxygen (oxidative or non-oxidative), is formed during the dehydrogenation. Inert gases (nitrogen) are introduced into the dehydrogenation zone when the dehydrogenation is carried out in the presence of oxygen with the oxygen-containing gas stream fed in, provided that no pure oxygen is fed in. If an oxygen-containing gas is fed in, its oxygen content is generally at least 40% by volume, preferably at least 80% by volume, particularly preferably at least 90% by volume, in particular technically pure oxygen with an oxygen content> 99 %, in order to avoid too high an inert gas portion in the product gas mixture. In addition, unreacted propane is present in the product gas mixture.

The propane dehydrogenation can in principle be carried out in all reactor types known from the prior art. A comparatively comprehensive description of the invention suitable reactor types also includes "Catalytica® ^® Studies Division, Oxidative Dehydrogenation and Alternative Dehydrogenation Proces- ses" (Study Number 4192 OD, 1993, 430 Ferguson Drive, Mountain View, California, 94043-5272, USA).

The dehydrogenation can be carried out as oxidative or non-oxidative dehydrogenation. The dehydration can be performed isothermally or adiabatically. The dehydrogenation can be carried out catalytically in a fixed bed, moving bed or fluidized bed reactor.

The oxidative catalytic propane dehydrogenation is preferably carried out autothermally. For this purpose, oxygen is additionally added to the reaction gas mixture of the propane dehydrogenation in at least one reaction zone and the hydrogen and / or hydrocarbon contained in the reaction gas mixture is at least partially mixed. burned, whereby at least part of the required Dehydrierwärme is generated in the at least one reaction zone directly in the reaction gas mixture.

One feature of non-oxidative driving versus oxidative driving is the at least intermediate formation of hydrogen, which is reflected in the presence of hydrogen in the dehydrogenation product gas. In oxidative dehydrogenation, there is no free hydrogen in the dehydrogenation product gas.

A suitable reactor form is the fixed bed tube or tube bundle reactor. In these, the catalyst (dehydrogenation catalyst and optionally special oxidation catalyst) is a fixed bed in a reaction tube or in a bundle of reaction tubes. Typical reaction tube internal diameters are about 10 to 15 cm. A typical Dehydrierrohrbündelreaktor comprises about 300 to 1000 reaction tubes. The temperature inside the reaction tube usually moves in the range of 300 to 1200 ° C, preferably in the range of 500 to 1000 ° C. The working pressure is usually between 0.5 and 8 bar, often between 1 and 2 bar when using a low water vapor dilution, but also between 3 and 8 bar when using a high steam dilution (according to the so-called "steam active reforming process" (STAR) Process) or the Linde process) for the dehydrogenation of propane or butane by Phillips Petroleum Co. Typical catalyst loadings (GHSV) are from 500 to 2000 h ^-1 , based on the hydrocarbon used. The catalyst geometry can be, for example, spherical or cylindrical (hollow or full).

The catalytic propane dehydrogenation can also be carried out in a heterogeneously catalyzed manner in a fluidized bed, in accordance with the Snampropoti / Yarsintez-FBD process. Conveniently, two fluidized beds are operated side by side, one of which is usually in the state of regeneration.

The working pressure is typically 1 to 2 bar, the dehydrated temperature usually 550 to 600 ° C. The heat required for the dehydrogenation can be introduced into the reaction system in that the dehydrogenation catalyst is preheated to the reaction temperature. By adding an oxygen-containing co-feed, the preheater can be partly dispensed with, and the heat required is generated directly in the reactor system by combustion of hydrogen and / or hydrocarbons in the presence of oxygen. Optionally, a hydrogen-containing co-feed may additionally be admixed.

The catalytic propane dehydrogenation can be carried out in a tray reactor. If the dehydrogenation is effected with the introduction of an oxygen-containing gas stream Totherm performed, it is preferably carried out in a tray reactor. This contains one or more successive catalyst beds. The number of catalyst beds may be 1 to 20, advantageously 1 to 6, preferably 1 to 4 and in particular 1 to 3. The catalyst beds are preferably flowed through radially or axially from the reaction gas. In general, such a tray reactor is operated with a fixed catalyst bed. In the simplest case, the fixed catalyst beds are arranged in a shaft furnace reactor axially or in the annular gaps of concentrically arranged cylindrical gratings. A shaft furnace reactor corresponds to a horde. The performance of dehydrogenation in a single shaft furnace reactor corresponds to one embodiment. In a further preferred embodiment, the dehydrogenation is carried out in a tray reactor with 3 catalyst beds.

In general, the amount of the oxygen-containing gas added to the reaction gas mixture is selected such that the amount of heat required for the dehydrogenation of the propane is produced by the combustion of hydrogen present in the reaction gas mixture and optionally of hydrocarbons present in the reaction gas mixture and / or of carbon present in the form of coke is produced. In general, the total amount of oxygen fed, based on the total amount of propane, is 0.001 to 0.8 mol / mol, preferably 0.001 to 0.6 mol / mol, particularly preferably 0.02 to 0.5 mol / mol. Oxygen can be used either as pure oxygen or as an oxygen-containing gas containing inert gases. In order to avoid high propane and propene losses in the workup (see below), however, it is essential that the oxygen content of the oxygen-containing gas used is high and at least 40 vol .-%, preferably at least 80 vol .-%, in particular - Preferably it is at least 90 vol .-%. Particularly preferred oxygen-containing gas is technically pure oxygen with an O ₂ content of about 99 vol .-%.

The hydrogen burned to generate heat is the hydrogen formed during the catalytic propane dehydrogenation and, if appropriate, the hydrogen gas additionally added to the reaction gas mixture. Preferably, sufficient hydrogen should be present so that the molar ratio H ₂ / O ₂ in the reaction gas mixture immediately after the introduction of oxygen is 1 to 10, preferably 2 to 5 mol / mol. This applies to multi-stage reactors for each intermediate feed of oxygen-containing and possibly hydrogen-containing gas.

The hydrogen combustion takes place catalytically. The dehydrogenation catalyst used generally also catalyzes the combustion of the hydrocarbons and of hydrogen with oxygen, so that in principle no special oxidation catalyst different from this one is required. In one embodiment, the reaction is carried out in the presence of one or more oxidation catalysts which are selective catalyze the combustion of hydrogen to oxygen in the presence of hydrocarbons. The combustion of these hydrocarbons with oxygen to CO, CO ₂ and water is therefore only to a minor extent. Preferably, the dehydrogenation catalyst and the oxidation catalyst are present in different reaction zones.

In multi-stage reaction, the oxidation catalyst may be present in only one, in several or in all reaction zones.

Preferably, the catalyst which selectively catalyzes the oxidation of hydrogen is disposed at the sites where higher oxygen partial pressures prevail than at other locations of the reactor, particularly near the oxygen-containing gas feed point. The feeding of oxygen-containing gas and / or hydrogen-containing gas can take place at one or more points of the reactor.

In one embodiment of the method according to the invention, an intermediate feed of oxygen-containing gas and of hydrogen-containing gas takes place before each tray of a tray reactor. In a further embodiment of the method according to the invention, the feed of oxygen-containing gas and of hydrogen-containing gas takes place before each horde except the first horde. In one embodiment, behind each feed point is a layer of a specific oxidation catalyst, followed by a layer of the dehydrogenation catalyst. In another embodiment, no special oxidation catalyst is present. The dehydrogenation temperature is generally 400 to 1100 ° C, the pressure in the last catalyst bed of the tray reactor generally 0.2 to 15 bar, preferably 1 to 10 bar, particularly preferably 1 to 5 bar. The load (GHSV) is generally 500 to 2000 h ^"1 , in high load mode also up to 100 000 h ^{" 1} , preferably 4000 to 16 000 IT. ¹

A preferred catalyst which selectively catalyzes the combustion of hydrogen contains oxides and / or phosphates selected from the group consisting of the oxides and / or phosphates of germanium, tin, lead, arsenic, antimony or bismuth. Another preferred catalyst which catalyzes the combustion of hydrogen contains a noble metal of VIII. And / or I. Nebengruppe.

The dehydrogenation catalysts used generally have a carrier and an active composition. The carrier is usually made of a heat-resistant oxide or mixed oxide. Preferably, the dehydrogenation catalysts contain a metal oxide selected from the group consisting of zirconia, zinc oxide, alumina, silica, titania, magnesia, lanthana, ceria and their mixtures, as carriers. The mixtures may be physical mixtures or chemical mixed phases such as magnesium or zinc-aluminum oxide mixed oxides. Preferred supports are zirconia and / or silica, particularly preferred are mixtures of zirconia and silica.

Suitable shaped catalyst body geometries are strands, stars, rings, saddles, spheres, foams and monoliths with characteristic dimensions of 1 to 100 mm.

The active composition of the dehydrogenation catalysts generally contain one or more elements of VIII. Subgroup, preferably platinum and / or palladium, more preferably platinum. In addition, the dehydrogenation catalysts may comprise one or more elements of main group I and / or II, preferably potassium and / or cesium. Furthermore, the dehydrogenation catalysts may contain one or more elements of the IM. Subgroup including the lanthanides and actinides, preferably lanthanum and / or cerium. Finally, the dehydrogenation catalysts may contain one or more elements of III. and / or IV. Main group, preferably one or more elements from the group consisting of boron, gallium, silicon, germanium, tin and lead, particularly preferably tin.

In a preferred embodiment, the dehydrogenation catalyst contains at least one element of subgroup VIII, at least one element of main group I and / or II, at least one element of IM. and / or IV. main group and at least one element of IM. Subgroup including the lanthanides and actinides.

For example, according to the invention, all dehydrogenation catalysts can be used which are described in WO 99/46039, US Pat. No. 4,788,371, EP-A 705,136, WO 99/29420, US Pat. No. 5,220,091, US Pat. No. 5,430,220, US Pat. No. 5,877,369, EP 0 1 17 146, DE-A 199 37 106, DE-A 199 37 105 and DE-A 199 37 107 are disclosed. Particularly preferred catalysts for the above-described variants of the autothermal propane dehydrogenation are the catalysts according to Examples 1, 2, 3 and 4 of DE-A 199 37 107.

The autothermal propane dehydrogenation is preferably carried out in the presence of steam. The added water vapor serves as a heat carrier and supports the gasification of organic deposits on the catalysts, whereby the coking of the catalysts counteracted and the service life of the catalysts is increased. The organic deposits are converted into carbon monoxide, carbon dioxide and possibly water. By dilution with water vapor, the degree of equilibrium is increased. The dehydrogenation catalyst can be regenerated in a manner known per se. Thus, steam can be added to the reaction gas mixture or, from time to time, an oxygen-containing gas can be passed over the catalyst charge at elevated temperature and the deposited carbon burned off. If appropriate, the catalyst is reduced after regeneration with a hydrogen-containing gas.

The product gas stream b can be separated into two partial streams, with a partial stream being returned to the autothermal dehydrogenation, in accordance with the cycle gas procedure described in DE-A 102 11 275 and DE-A 100 28 582.

The propane dehydrogenation can be carried out as an oxidative dehydrogenation. The oxidative propane dehydrogenation can be carried out as a homogeneous oxidative dehydrogenation or as a heterogeneously catalyzed oxidative dehydrogenation.

If the propane dehydrogenation is designed as a homogeneous oxydehydrogenation in the context of the process according to the invention, it can be prepared in principle as described in US-A 3,798,283, CN-A 1, 105,352, Applied Catalysis, 70 (2), 1991, p to 187, Catalysis Today 13, 1992, pp. 673 to 678 and the earlier application DE-A 1 96 22 331.

The temperature of the homogeneous oxydehydrogenation is generally from 300 to 700 ° C, preferably from 400 to 600 ° C, more preferably from 400 to 500 ° C. The pressure can be 0.5 to 100 bar or 1 to 50 bar. Often it will be at 1 to 20 bar, especially at 1 to 10 bar.

The residence time of the reaction gas mixture under oxydehydrogenation conditions is usually 0.1 or 0.5 to 20 seconds, preferably 0.1 or 0.5 to 5 seconds. a tube furnace or a tube bundle reactor may be used, e.g. a countercurrent furnace with flue gas as the heat carrier, or a tube bundle reactor with molten salt as the heat transfer medium.

The propane to oxygen ratio in the starting mixture to be used may be 0.5: 1 to 40: 1. The molar ratio of propane to molecular oxygen in the starting mixture is preferably <6: 1, preferably <5: 1. As a rule, the aforesaid ratio will be> 1: 1, for example> 2: 1. The starting mixture may comprise further, essentially inert constituents, such as H ₂ O, CO ₂ , CO, N ₂ , noble gases and / or propene. Propene may be included in the refinery's C ₃ fraction. It is favorable for a homogeneous oxidative dehydrogenation of propane to propene if the ratio of the surface area of the reaction Volume to the volume of the reaction space is as small as possible, since the homogeneous oxidative propane dehydrogenation proceeds according to a radical mechanism and the reaction space surface usually acts as a radical scavenger. Particularly favorable surface materials are aluminum oxides, quartz glass, borosilicates, stainless steel and aluminum.

If, in the context of the process according to the invention, the first reaction stage is designed as a heterogeneously catalyzed oxydehydrogenation, this can in principle be carried out as described in US-A 4,788,371, CN-A 1, 073,893, Catalysis Letters 23 (1994) 103-106, W. Zhang Gaodeng Xuexiao Huaxue Xuebao, 14 (1993) 566, Z. Huang, Shiyou Huangong, 21 (1992) 592, WO 97/36849, DE-A 1 97 53 817, US-A 3,862,256, US-A 3,887,631, DE-A 1 95 30 454, US Pat. No. 4,341,664, J. of Catalysis 167, 560-569 (1997), J. of Catalysis 167, 550-559 (1997), Topics in Catalysis 3 (1996) 265 275, US Pat. No. 5,086,032, Catalysis Letters 10 (1991) 181-192, Ind. Eng. Chem. Res. 1996, 35, 14-18, US-A 4,255,284, Applied Catalysis A: General, 100 (1993) 1111-133, J. of Catalysis 148, 56-67 (1994), V. Cortes Corberan and S. Vic Bellόn (Editors), New Developments in Selective Oxidation II, 1994, Elsevier Science BV, pp. 305-313, 3rd World Congress on Oxidation Catalysis RK Grasselli, ST. Oyama, A.M. Gaffney and J.E. Lyons (Editors), 1997, Elsevier Science B.V., p. 375 ff. In particular, all the oxydehydrogenation catalysts mentioned in the abovementioned publications can be used. The said for the aforementioned writings also applies to:

i) Otsuka, K .; Uragami, Y .; Komatsu, T .; Hatano, M. in Natural Gas Conversion, Stud Surf. Be. Catal .; Holmen A .; Jens, K.-J .; Kolboe, S., Eds .; Elsevier Science: Amsterdam, 1991; Vol. 61, p 15; ii) Seshan, K .; Swaan, H.M .; Smits, R.H. H .; van Ommen, J.G .; Ross, J.R.H. in New Developments in Selective Oxidation; Stud. Surf. Be. Catal .; Centi, G .; Trifirö, F., Eds .; Elsevier Science: Amsterdam 1990; Vol. 55, p 505; iii) Smits, R.H.H .; Seshan, K .; Ross, J.R.H. in New Developments in Selective Oxidation by Heterogeneous Catalysis; Stud. Surf. Be. Catal .; Ruiz, P .; Delmon, B.,

eds .; Elsevier Science: Amsterdam, 1992 a; Vol. 72, p 221; iv) Smits, R.H.H .; Seshan, K .; Ross, J.R. Proceedings, Symposium on Catalytic Selective Oxidation, Washington DC; American Chemical Society: Washington, DC, 1992b; 1 121; v) Mazzocchia, C; Aboumrad, C; Daigne, C; Tempesti, E .; Herrmann, J. M .; Thomas, G. Catal. Lett. 1991, 10, 181;

vi) Bellusi, G .; Conti, G .; Perathonar, S .; Trifirö, F. Proceedings, Symposium on Catalytic Selective Oxidation, Washington, DC; American Chemical Society: Washington, DC, 1992; p 1242; vii) Ind. Eng. Chem. Res. 1996, 35, 2137-2133 and viii) Symposium on Heterogeneous Hydrocarbon Oxidation Presented before the Division of Petroleum Chemistry, Inc. 211 th National Meeting, American Chemical Society, New Orleans, LA, March 24-29, 1996.

Particularly suitable oxydehydrogenation catalysts are the multimetal oxide materials or catalysts A of DE-A 1 97 53 817, the multimetal oxide materials or catalysts A mentioned as being preferred being very particularly advantageous. In other words, the active compounds used are, in particular, multimetal oxide materials of the general formula I.

M ¹ _a M _Oi _ _b M ² _b O _x (I), with

M ¹ = Co, Ni, Mg, Zn, Mn and / or Cu,

M ² = W, V, Te, Nb, P, Cr, Fe, Sb, Ce, Sn and / or La, a = 0.5 to 1.5, b = 0 to 0.5 and x = a number which is determined by the valence and frequency of the elements other than oxygen in I,

into consideration.

Further multimetal oxide compositions suitable as oxydehydrogenation catalysts are mentioned below:

Suitable Mo-V-Te / Sb-Nb-O multimetal oxide catalysts are described in EP-A 0 318 295, EP-A 0 529 853, EP-A 0 603 838, EP-A 0 608 836, EP-A 0 608 838 EP-A 0 895 809, EP-A 0 962 253, EP-A 1 192 987, DE-A 198 35 247, DE-A 100 51 419 and DE-A 101 19 933.

Suitable Mo-V-Nb-O multimetal oxide catalysts are described, inter alia, in EM Thorsteinson, TP Wilson, FG Young, PH Kasei, Journal of Catalysis 52 (1978), pages 16-132 and in US 4,250,346 and EP-A 0294 845th

Suitable Ni-X-O-Multimetalloxidkatalysatoren, with X = Ti, Ta, Nb, Co, Hf, W, Y, Zn, Zr, Al, are described in WO 00/48971.

In principle, suitable active masses can be prepared in a simple manner by using a suitable source of their components as intimately as possible. preferably finely divided, their stoichiometry correspondingly composed dry mixture and this calcined at temperatures of 450 to 1000 ° C. The calcination can be carried out both under inert gas and under an oxidative atmosphere such as air (mixture of inert gas and oxygen) as well as under reducing atmosphere (eg mixture of inert gas, oxygen and NH ₃ , CO and / or H ₂ ). Suitable sources of the components of the multimetal oxide active materials are oxides and / or compounds which can be converted into oxides by heating, at least in the presence of oxygen. In addition to the oxides, suitable starting compounds are in particular halides, nitrates, formates, oxalates, citrates, acetates, carbonates, amine complex salts, ammonium salts and / or hydroxides.

The multimetal oxide compositions can be used for the process according to the invention in shaped both in powder form and to specific catalyst geometries, wherein the shaping can take place before or after the final calcination. Suitable unsupported catalyst geometries are e.g. Solid cylinder or hollow cylinder with an outer diameter and a length of 2 to 10 mm. In the case of the hollow cylinder, a wall thickness of 1 to 3 mm is appropriate. Suitable hollow cylinder geometries are e.g. 7mm x 7mm x 4mm or 5mm x 3mm x 2mm or 5mm x 2mm x 2mm (each length x outside diameter x inside diameter). Of course, the solid catalyst can also have ball geometry, wherein the ball diameter can be 2 to 10 mm.

Of course, the shaping of the powdered active composition or its powdery, not yet calcined precursor composition can also be effected by application to preformed inert catalyst supports. The layer thickness of the powder mass applied to the carrier body is expediently chosen in the range from 50 to 500 mm, preferably in the range from 150 to 250 mm. As carrier materials, it is possible to use customary porous or non-porous aluminum oxides, silicon dioxide, thorium dioxide, zirconium dioxide, silicon carbide or silicates, such as magnesium silicate or aluminum silicate. The carrier bodies may be regularly or irregularly shaped, with regularly shaped carrier bodies having a marked surface roughness, e.g. Balls, hollow cylinders or saddles with dimensions in the range of 1 to 100 mm are preferred. Suitable is the use of substantially nonporous, surface roughness, spherical steatite supports whose diameter is 1 to 8 mm, preferably 4 to 5 mm.

The reaction temperature of the heterogeneously catalyzed oxydehydrogenation of propane is generally from 300 to 600 ° C, usually from 350 to 500 ° C. Of the

Pressure is 0.2 to 15 bar, preferably 1 to 10 bar, for example 1 to 5 bar. Pressures above 1 bar, eg 1, 5 to 10 bar, have proven to be particularly advantageous. In general, the heterogeneously catalyzed oxydehydrogenation of the propane takes place on a fixed catalyst bed. The latter is expediently poured into the tubes of a tube bundle reactor, as described, for example, in EP-A 700 893 and in EP-A 700 714 and in the literature cited in these publications. The average residence time of the reaction gas mixture in the catalyst bed is normally 0.5 to 20 seconds. The propane to oxygen ratio in the reaction gas starting mixture to be used for the heterogeneously catalyzed propane oxydehydrogenation may be 0.5: 1 to 40: 1 , It is advantageous if the molar ratio of propane to molecular oxygen in the starting gas mixture is <6: 1, preferably <5: 1. In general, the aforementioned ratio will be> 1: 1, for example 2: 1. The starting gas mixture may comprise further, substantially inert constituents such as H ₂ O, CO ₂ , CO, N ₂ , noble gases and / or propene. In addition, Cr, C ₂ and C ₄ hydrocarbons may also be present to some extent.

The product gas stream b when leaving the dehydrogenation zone is generally under a pressure of 0.2 to 15 bar, preferably 1 to 10 bar, more preferably 1 to 5 bar, and has a temperature in the range of 300 to 700 ° C.

In the propane dehydrogenation, a gas mixture is obtained, which generally has the following composition: 10 to 80% by volume of propane, 5 to 50% by volume of propene, 0 to 20% by volume of methane, ethane, ethene and C ₄ ⁺ Hydrocarbons, 0 to 30% by volume of carbon oxides, 0 to 70% by volume of steam and 0 to 25% by volume of hydrogen and 0 to 50% by volume of inert gases.

In the preferred autothermal propane dehydrogenation, a gas mixture is obtained, which generally has the following composition: 10 to 80 vol .-% propane, 5 to 50 vol .-% propene, 0 to 20 vol .-% of methane, ethane, ethene and C ₄ ⁺ hydrocarbons, 0.1 to 30% by volume of carbon oxides, 1 to 70% by volume of steam and 0.1 to 25% by volume of hydrogen and 0 to 30% by volume of inert gases.

In process part C), water is first separated from the product gas stream b. The separation of water is carried out by condensation by cooling and optionally compressing the product gas stream b and can be carried out in one or more cooling and optionally compression stages. In general, the product gas stream b is cooled to a temperature in the range from 20 to 80.degree. C., preferably from 40 to 65.degree. In addition, the product gas stream can be compressed, generally to a pressure in the range of 2 to 40 bar, preferably 5 to 20 bar, particularly preferably 10 to 20 bar. In one embodiment of the process according to the invention, the product gas stream b is passed through a cascade of heat exchangers and initially cooled to a temperature in the range of 50 to 200 ° C and then in a quench tower with water to a temperature of 40 to 80 ° C, for example 55 ° C further cooled. Most of the water vapor condenses here, but also some of the C ₄ ⁺ hydrocarbons contained in the product gas stream b, in particular the C ₅ ⁺ hydrocarbons. Suitable heat exchangers are, for example, direct heat exchangers and countercurrent heat exchangers, such as gas-gas countercurrent heat exchangers, and air coolers.

There is obtained a water vapor depleted product gas stream c. This generally contains 0 to 10 vol .-% water vapor. For practically complete removal of water from the product gas stream c, drying using a molecular sieve, in particular molecular sieve 3A, 4A, 13X or aluminum oxides, or membranes may be preferred when using certain adsorbents in step D).

Before carrying out step (a) of the process according to the invention for the technical recovery of propene, carbon dioxide can be separated off from the gas stream c by scrubbing the gas or by adsorption on solid adsorbents. The carbon dioxide gas scrubber may be preceded by a separate combustion stage in which carbon monoxide is selectively oxidized to carbon dioxide.

For CU ₂ separation, sodium hydroxide solution, potassium hydroxide solution or an alkanolamine solution is generally used as the washing liquid; preference is given to using an activated N-methyldiethanolamine solution. In general, before carrying out the gas scrubbing, the product gas stream c is compressed to a pressure in the range from 5 to 25 bar by single or multi-stage compression. It is possible to obtain a carbon dioxide-depleted stream c having a CO ₂ content of generally <1000 ppm, preferably <100 ppm, more preferably <20 ppm.

However, it is preferred to separate off CO ₂ by sorption on suitable solid sorbents, for example molecular sieve 13X, calcium oxide, barium oxide, magnesium oxide or hydrotalcites.

In a particularly preferred embodiment, the purified product stream thus obtained from propene production constitutes the gas stream containing at least propane and propene used in the process according to the invention for the industrial recovery of propene. The porous organometallic framework contains at least one at least one metal ion coordinated at least bidentate organic compound. This organometallic framework (MOF) is described, for example, in US Pat. No. 5,648,508, EP-A-0 790 253, MOKeeffe et al., J. Sol. State Chem., 152 (2000), pages 3 to 20, H. Li et al., Nature 402 (1999), p. 276, M. Eddaoudi et al., Topics in Catalysis 9, (1999), p. 105 11-11, B. Chen et al., Science 291_, (2001), pages 1021 to 1023 and DE-A-101 11 230, WO-A 2005/049892 and AC Sudik et al., J. Am. Chem. Soc. 127 (2005), 7110-71 18.

The organometallic frameworks according to the present invention contain pores, in particular micro and / or mesopores. Micropores are defined as those having a diameter of 2 nm or smaller and mesopores are defined by a diameter in the range of 2 to 50 nm, each according to the definition as defined by Pure & Applied Chem. 57, (1485), 603-619 , in particular on page 606. The presence of micro- and / or mesopores can be checked by means of sorption measurements, these measurements determining the MOF's absorption capacity for nitrogen at 77 Kelvin according to DIN 66131 and / or DIN 66134.

Preferably, the specific surface area - calculated according to the Langmuir model according to DIN 66135 (DIN 66131, 66134) for a framework material in powder form is more than 5 m ² / g, more preferably more than 10 m ² / g, more preferably more than 50 m ² / g, more preferably more than 500 m ² / g, even more preferably more than 1000 m ² / g and particularly preferably more than 1500 m ² / g.

MOF shaped bodies can have a lower active surface; but preferably more than 10 m ² / g, more preferably more than 50 m ² / g, even more preferably more than 500 m ² / g, in particular more than 1000 m ² / g.

In the context of the present invention, the maximum of the pore diameter distribution should be at least 4 Å. This maximum is preferably between 4.3 and 20 Å. Particularly preferred is the range between 5 and 13 Å.

The metal component in the framework material according to the present invention is preferably selected from groups Ia, IIa, IIIa, IVa to Villa and Ib to VIb. Further preferred are the groups IIa, IMb, IMa to VIa of the Periodic Table of the Elements and the lanthanides, V, Mn, Fe, Ni, Co. Particularly preferred are Mg, Ca, Sr, Ba,

Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ro, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu,

Ag, Au, Zn, Cd, Hg, Al, Ga, In, Tl, Si, Ge, Sn, Pb, As, Sb and Bi. Further more preferred are Mg, Al, In, Cu, Zn, Fe, Ni, Co, Mn, Zr, Ti, Sc, Y, La, Ce. More preferred Mg, Al, In, Cu, Zn, Fe, Zr, Y. In the case of copper, preference is given to MOF types which have no free Cu coordination site.

With regard to the ions of these elements, mention should particularly be made of Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , Sc ³⁺ , Y ³⁺ , Ti ⁴⁺ , Zr ⁴⁺ , Hf ⁴⁺ , V ⁴⁺ , V ³⁺ , V ²⁺ , Nb ³⁺ , Ta ³⁺ , Cr ³⁺ , Mo ³⁺ , W ³⁺ , Mn ³⁺ , Mn ²⁺ , Re ³⁺ , Re ²⁺ , Fe ³⁺ , Fe ²⁺ , Ru ³⁺ , Ru ²⁺ , Os ³⁺ , Os ²⁺ , Co ³⁺ , Co ²⁺ , Rh ²⁺ , Rh ⁺ , Ir ²⁺ , Ir ⁺ , Ni ²⁺ , Ni ⁺ , Pd ^{2 +} , Pd ⁺ , Pt ²⁺ , Pt ⁺ , Cu ²⁺ , Cu ⁺ , Ag ⁺ , Au ⁺ , Zn ²⁺ , Cd ²⁺ , Hg ²⁺ , Al ³⁺ , Ga ³⁺ , In ³⁺ , Tl ³⁺ , Si ⁴⁺ , Si ²⁺ , Ge ⁴⁺ , Ge ²⁺ , Sn ⁴⁺ , Sn ²⁺ , Pb ⁴⁺ , Pb ²⁺ , As ⁵⁺ , As ³⁺ , As ⁺ , Sb ⁵⁺ , Sb ³⁺ , Sb ⁺ , Bi ⁵⁺ , Bi ³⁺ and Bi ⁺ .

The term "at least bidentate organic compound" refers to an organic compound containing at least one functional group capable of having at least two, preferably two coordinative, bonds to a given metal ion, and / or to two or more, preferably two, metal atoms, respectively to form a coordinative bond.

Examples of functional groups which can be used to form the abovementioned coordinative bonds are, for example, the following functional groups: -CO ₂ H, -CS ₂ H, -NO ₂ , -B (OH) ₂ , -SO ₃ H, - Si (OH) ₃ , -Ge (OH) ₃ , -Sn (OH) ₃ , -Si (SH) ₄ , -Ge (SH) ₄ , -Sn (SH) ₃ , -PO ₃ H, -AsO ₃ H , -AsO ₄ H, -P (SH) ₃ , -As (SH) ₃ , -CH (RSH) ₂ , -C (RSH) ₃ -CH (RNH ₂ ), -C (RNH ₂ ) ₃ , -CH (ROH) ₂ , -C (ROH) ₃ , -CH (RCN) ₂ , -C (RCN) ₃ , wherein R, for example, preferably an alkylene group having 1, 2, 3, 4 or 5 carbon atoms such as a methylene, ethylene , n-propylene, i-propylene, n-butylene, i-butylene, tert-butylene or n-pentylene group, or an aryl group containing 1 or 2 aromatic nuclei such as 2 Cβ rings, which may be condensed may be independently substituted with at least one substituent, and / or independently of one another in each case at least one heteroatom such as may contain N, O and / or S. According to likewise preferred embodiments, functional groups are to be mentioned in which the abovementioned radical R is absent. In this regard, inter alia, -CH (SH) ₂ , -C (SH) ₃ , -CH (NH ₂ ) ₂ , -C (NH ₂ J ₃ , -CH (OH) ₂ , -C (OH) ₃ , -CH (CN) ₂ or -C (CN) ₃ .

The at least two functional groups can in principle be bound to any suitable organic compound, as long as it is ensured that the organic compound having these functional groups is capable of forming the coordinative bond and the preparation of the framework.

The organic compounds which contain the at least two functional groups are preferably derived from a saturated or unsaturated aliphatic compound. bond or an aromatic compound or an aliphatic as well as aromatic compound.

The aliphatic compound or the aliphatic portion of the both aliphatic and aromatic compound may be linear and / or branched and / or cyclic, wherein also several cycles per compound are possible. More preferably, the aliphatic compound or the aliphatic portion of the both aliphatic and aromatic compound contains 1 to 15, more preferably 1 to 14, further preferably 1 to 13, further preferably 1 to 12, further preferably 1 to 11 and particularly preferably 1 to 10 C atoms such as 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 C atoms. Methane, adamantane, acetylene, ethylene or butadiene are particularly preferred in this case.

The aromatic compound or the aromatic part of both aromatic and aliphatic compound may have one or more cores, such as two, three, four or five cores, wherein the cores may be separated from each other and / or at least two nuclei in condensed form. Particularly preferably, the aromatic compound or the aromatic part of the both aliphatic and aromatic compound one, two or three nuclei, with one or two nuclei being particularly preferred. Independently of each other, furthermore, each nucleus of the named compound may contain at least one heteroatom, such as, for example, N, O, S, B, P, Si, Al, preferably N, O and / or S. More preferably, the aromatic compound or the aromatic moiety of the both aromatic and aliphatic compounds contains one or two C ₆ cores, the two being either separately or in condensed form. Benzene, naphthalene and / or biphenyl and / or bipyridyl and / or pyridyl may in particular be mentioned as aromatic compounds.

Examples include trans-muconic acid or fumaric acid or phenylenebisacrylic acid.

The at least bidentate organic compound is preferably derived from a di-, tri- or tetracarboxylic acid or its sulfur analogs. Sulfur analogues are the functional groups -C (= O) SH and its tautomer and C (= S) SH, which can be used instead of one or more carboxylic acid groups.

The term "derive" in the context of the present invention means that the at least bidentate organic compound can be present in the framework material in partially deprotonated or completely deprotonated form. least bidentate organic compound containing further substituents such as -OH, -NH ₂ , -OCH ₃ , -CH ₃ , -NH (CH ₃ ), -N (CH ₃ J ₂ , -CN and halides.

For example, in the context of the present invention dicarboxylic acids such as

Oxalic acid, succinic acid, tartaric acid, 1,4-butanedicarboxylic acid, 4-oxo-pyran-2,6-dicarboxylic acid, 1,6-hexanedicarboxylic acid, decanedicarboxylic acid, 1,8-heptadecanedicarboxylic acid, 1,9-heptadecanedicarboxylic acid, heptadecane dicarboxylic acid, acetylenedicarboxylic acid. carboxylic acid, 1, 2-benzenedicarboxylic acid, 2,3-pyridinedicarboxylic acid, pyridine-2,3-dicarboxylic acid, 1,3-butadiene-1,4-dicarboxylic acid, 1,4-benzenedicarboxylic acid, p-benzenedicarboxylic acid, imidazole acid. 2,4-dicarboxylic acid, 2-methyl-quinoline-3,4-dicarboxylic acid, quinoline-2,4-dicarboxylic acid, quinoxaline-2,3-dicarboxylic acid, 6-chloroquinoxaline-2,3-dicarboxylic acid, 4,4-diaminophenylmethane 3,3'-dicarboxylic acid, quinoline-3,4-dicarboxylic acid, 7-chloro-4-hydroxyquinoline-2,8-dicarboxylic acid, diimide dicarboxylic acid, pyridine-2,6-dicarboxylic acid, 2-methylimidazole-4,5-dicarboxylic acid , Thiophene-3,4-dicarboxylic acid, 2-isopropylimidazole-4,5-dicarboxylic acid, tetrahydropyran-4,4'-dicarboxylic acid, perylene-3,9-dicarboxylic acid, perylenedicarboxylic acid, pluriol E 200-dicarboxylic acid, 3 , 6-dioxaoctanedicarboxylic acid, 3,5-cyclohexadiene-1,2-dicarboxylic acid, octanedicarboxylic acid, pentane-3,3-dicarboxylic acid, 4,4'-diamino-1,1'-diphenyl-3,3'-dicarboxylic acid, 4,4'-diaminodiphenyl-3,3'-dicarboxylic acid, benzidine-3,3'-dicarboxylic acid, 1,4-bis (phenylamino) benzene-2,5-dicarboxylic acid, 1,1'-dinaphthyl-5.5 '-dicarboxylic acid, 7-chloro-8-methylquinoline-2,3-dicarboxylic acid, 1-anilinoanthraquinone-2,4'-dicarboxylic acid, polytetrahydrofuran-250-dicarboxylic acid, 1,4-bis- (carboxymethyl) -piperazine-2,3 dicarboxylic acid, 7-chloroquinoline-3,8-dicarboxylic acid, 1- (4-carboxy) -phenyl-3- (4-chloro) -phenyl-pyrazoline-4,5-dicarboxylic acid, 1, 4,5,6,7 , 7, -hexa-chloro-5-norbornene-2,3-dicarboxylic acid, phenylindane dicarboxylic acid, 1, 3-dibenzyl-2-oxo-imidazolidine-4,5-dicarboxylic acid, 1, 4-cyclohexanedicarboxylic acid, naphthalene-1, 8-dicarboxylic acid, 2-benzoylbenzene-1,3-dicarboxylic acid, 1,3-dibenzyl-2-oxo-imidazolidine-4,5-cis-dicarboxylic acid, 2,2'-biquinoline-4,4-dicarboxylic acid , Pyridine-3,4-dicarboxylic acid, 3,6,9-trioxa undecanedicarboxylic acid, O-hydroxybenzophenone dicarboxylic acid, Pluriol E 300 dicarboxylic acid, Pluriol E 400 dicarboxylic acid, Pluriol E 600 dicarboxylic acid, pyrazole-3,4-dicarboxylic acid, 2,3-pyrazine dicarboxylic acid, 5,6-dimethyl-2,3-dicarboxylic acid. pyrazine dicarboxylic acid, 4,4'-diaminodiphenyl ether diimide dicarboxylic acid, 4,4'-diaminodiphenylmethane diimide dicarboxylic acid, 4,4'-diaminodiphenylsulfonediimide dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1, 3-adamantane dicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphtha lindicarboxylic acid, 8-methoxy-2,3-naphthalenedicarboxylic acid, 8-nitro-2,3-naphthalenedicarboxylic acid, 8-sulfo-2,3-naphthalenedicarboxylic acid, anthracene-2,3-dicarboxylic acid, 2 ', 3'-diphenyl- p-terphenyl-4,4'-dicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, imidazole-4,5-dicarboxylic acid, 4 (1 H) -oxo-thiochromene-2,8-dicarboxylic acid, 5-tert-butylcarboxylic acid, Butyl-1,3-benzenedicarboxylic acid, 7,8-quinolinedicarboxylic acid, 4,5-imidazoledicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, hexatriacontanedicarboxylic acid, tetradecanedicarbo nsäu- Re, 1, 7-heptadicarboxylic acid, 5-hydroxy-1,3-benzenedicarboxylic acid, pyrazine-2,3-dicarboxylic acid, furan-2,5-dicarboxylic acid, 1-nonene-6,9-dicarboxylic acid, eicosendicarboxylic acid, 4, 4'-dihydroxydiphenylmethane-3,3'-dicarboxylic acid, 1-amino-4-methyl-9,10-dioxo-9,10-dihydroanthracene-2,3-dicarboxylic acid, 2,5-pyridinedicarboxylic acid, cyclohexene-2, 3-dicarboxylic acid, 2,9-dichlorofluorubin-4,1-dicarboxylic acid, 7-chloro-3-methylquinoline-6,8-dicarboxylic acid, 2,4-dichlorobenzophenone-2 ', 5'-dicarboxylic acid, 1,3-benzenedicarboxylic acid , 2,6-pyridinedicarboxylic acid, 1-methylpyrrole-3,4-dicarboxylic acid, 1-benzyl-1H-pyrrole-3,4-dicarboxylic acid, anthraquinone-1, 5-dicarboxylic acid, 3,5-

Pyrazoledicarboxylic acid, 2-nitrobenzene-1,4-dicarboxylic acid, heptane-1, 7-dicarboxylic acid, cyclobutane-1,1-dicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 5,6-dehydronorbornane-2,3-dicarboxylic acid or 5-ethyl 2,3-pyridinedicarboxylic acid, tricarboxylic acids such as

2-hydroxy-1,2,3-propanetricarboxylic acid, 7-chloro-2,3,8-quinolinetricarboxylic acid, 1, 2,4-benzenetricarboxylic acid, 1, 2,4-butanetricarboxylic acid, 2-phosphono-1, 2,4- butanetricarboxylic acid, 1, 3,5-benzenetricarboxylic acid, 1-hydroxy-1,2,3-propanetricarboxylic acid, 4,5-dihydro-4,5-dioxo-1H-pyrrolo [2,3-F] quinoline -2,7,9-tricarboxylic acid, 5-acetyl-3-amino-6-methylbenzene-1, 2,4-tricarboxylic acid, 3-amino-5-benzoyl-6-methylbenzene-1, 2,4-tricarbon acid, 1,2,3-propanetricarboxylic acid or auric tricarboxylic acid, or tetracarboxylic acids such as

1, 1-Dioxidperylo [1, 12-BCD] thiophene-3,4,9,10-tetracarboxylic acid, perylenetetracarboxylic acids such as perylene-3,4,9,10-tetracarboxylic acid or perylene-1,12-sulfone-3, 4,9,10-tetracarboxylic acid, butanetetracarboxylic acids such as 1, 2,3,4-butanetetracarboxylic acid or meso-1,2,3,4-butanetetracarboxylic acid, decane-2,4,6,8-tetracarboxylic acid, 1, 4, 7, 10,13,16-hexaoxacyclooctadecane-2,3,11,12-tetracarboxylic acid, 1, 2,4,5-benzenetetracarboxylic acid, 1,2,11,12-dodecantetracarboxylic acid, 1, 2,5,6-hexanetetracarboxylic acid, 1, 2,7,8-octanetetracarboxylic acid, 1, 4,5,8-naphthalenetetracarboxylic acid, 1,2,9,10-decantetracarboxylic acid, benzophenonetetracarboxylic acid, 3,3 ', 4,4'-benzophenonetetracarboxylic acid, tetrahydrofurantetracarboxylic acid or To call cyclopentanetetracarboxylic acids such as cyclopentane-1, 2,3,4-tetracarboxylic acid.

Very particular preference is given to using at least mono-, di-, tri-, tetra- or higher-nuclear aromatic di-, tri- or tetracarboxylic acids, where each of the cores can contain at least one heteroatom, where two or more nuclei have identical or different heteroatoms may contain. For example, preference is given to monocarboxylic dicarboxylic acids, monocarboxylic tricarboxylic acids, monocarboxylic tetracarboxylic acids, dicercaric dicarboxylic acids, dicercaric tricarboxylic acids, dicercaric tetracarboxylic acids, tricyclic dicarboxylic acids, tricarboxylic tricarboxylic acids, tricarboxylic tetracarboxylic acids, tetracyclic dicarboxylic acids, tetracyclic tricarboxylic acids and / or tetracyclic tetracarboxylic acids. Suitable heteroatoms are, for example, N, O, S, B, P, Si, Al, preferred heteroatoms here are N, S and / or O. As a suitable substituent in this regard, inter alia, -OH, a nitro group, an amino group or an alkyl or To name alkoxy group.

Particularly preferred as the at least bidentate organic compounds are acetylenedicarboxylic acid (ADC), benzenedicarboxylic acids, naphthalenedicarboxylic acids, biphenyldicarboxylic acids such as 4,4'-biphenyldicarboxylic acid (BPDC), bipidinedicarboxylic acids such as 2,2'-bipyridinedicarboxylic acids such as 2,2'-bipyridine 5,5'-dicarboxylic acid, benzene tricarboxylic acids such as 1, 2,3-benzenetricarboxylic acid or 1, 3,5-benzenetricarboxylic acid (BTC), adamantane tetracarboxylic acid (ATC), adamantane dibenzoate (ADB) benzene tribenzoate (BTB), methanetetrabenzoate (MTB ), Adamantane tetrabenzoate or dihydroxyterephthalic acids such as 2,5-dihydroxyterephthalic acid (DHBDC).

Isophthalic acid, terephthalic acid, 2,5-dihydroxyterephthalic acid, 1,2,3-benzenetricarboxylic acid, 1,3,5-benzenetricarboxylic acid, 2,2'-bipyridine-5,5'-dicarboxylic acid, aminoterephthalic acid or diaminoterephthalic acid are very particularly preferably used ,

In addition to these at least bidentate organic compounds, the MOF may also comprise one or more monodentate ligands.

Suitable solvents for the preparation of the MOF include i.a. Ethanol, dimethylformamide, toluene, methanol, chlorobenzene, diethylformamide, dimethyl sulfoxide, water, hydrogen peroxide, methylamine, sodium hydroxide solution, N-methylpolidone ether, acetonitrile, benzyl chloride, triethylamine, ethylene glycol and mixtures thereof. Other metal ions, at least bidentate organic compounds and solvents for the production of MOF include i.a. in US Pat. No. 5,648,508 or DE-A 101 11 230.

The pore size of the MOF can be controlled by choice of the appropriate ligand and / or the at least bidentate organic compound. Generally, the larger the organic compound, the larger the pore size. The pore size is preferably from 0.2 nm to 30 nm, more preferably the pore size is in the range from 0.3 nm to 3 nm, based on the crystalline material.

In a MOF shaped body, however, larger pores also occur whose size distribution can vary. Preferably, however, more than 50% of the total pore volume, in particular more than 75%, of pores having a pore diameter of up to 1000 nm is formed. Preferably, however, a majority of the pore volume is formed by pores of two diameter ranges. It is therefore more preferable if more than 25% of the total pore volume, in particular more than 50% of the total pore volume of pores is formed, which are in a diameter range of 100 nm to 800 nm and if more than 15% of the total pore volume, in particular more than 25% of the total pore volume is formed by pores which are in a diameter range of up to 10 nm. The pore distribution can be determined by means of mercury porosimetry.

Examples of very particularly suitable MOFs are Cu-BTC (BTC = 1, 3,5-benzenetricarboxylic acid), Al-terephthalic acid, Cu-terephthalic acid TEDA, Zn-terephthalic acid (MOF-5), Zn-terephthalic acid TEDA, MOF -74, Zn-naphthalene-DC (IRMOF-8), Al-aminoterephthalic acid.

The organometallic frameworks are generally used as moldings, for example as random beds of spheres, rings, strands or tablets or as ordered internals such as packings, honeycomb bodies and monoliths.

The production of moldings is described, for example, in WO-A 03/102 000. Preference is given to the use of moldings which are packed as densely as possible. Therefore, the shaped bodies at their narrowest point preferably at most 3 mm, more preferably at most 2 mm, most preferably at most 1, 5 mm in diameter. Very particular preference is given to moldings in tablet form. Alternatively, an installation in the form of a monolithic structure, since the large channels are also good to flush, while the material in the walls also sits very tightly packed.

In step (a) of the process according to the invention for the technical recovery of propene, no complete separation of the propene from the other gas constituents is required. The aim is rather as complete as possible loading of the adsorbent with pure propene. Since the adsorption coefficient of propene to the adsorbent is higher than that of the other gas constituents, other gas constituents are successively displaced from the adsorption sites, so that finally propene is selectively adsorbed. This applies in particular to the propane present in the gas stream.

In the event that the gas stream finds its origin from the propane dehydrogenation, the partial flow having the propane can be returned to the propane dehydrogenation. Typically, the adsorbent is in an adsorber. In addition to organometallic framework material, the adsorbent or the adsorber may contain other adsorbents such as molecular sieves or the like.

Preferably, the adsorber reactor is part of an adsorber system comprising at least three adsorbers which operate out of phase.

This makes it possible to carry out the release of the propene according to step (b) of the process according to the invention for the production of propene in quasi-continuous mode.

The release of the propene according to step (b) of the process according to the invention for the technical recovery of propene is preferably carried out by changing at least one of the physical parameters selected from the group consisting of pressure and temperature. Preferably, at least one pressure change takes place.

The release by pressure change can be done by pressure reduction to the application of vacuum. In the context of the present invention, however, the reduction of the partial pressure of propene is sufficient to release it. This can be done, for example, by displacing the propene with inert gas, which can later be easily separated again.

Step (a) of the process according to the invention for the technical recovery of propene represents an adsorption step, wherein step (b) of the process according to the invention for the technical recovery of propene represents a desorption step. If the adsorption and the desorption occur under changing pressure and / or temperature, numerous possibilities of a technical realization are known to the person skilled in the art.

All have in common that at least two, preferably three, more preferably at least four adsorbers are operated in parallel, of which at least two, but preferably all work out of phase with respect to the other adsorber. Possible variants are a) a pressure swing adsorption (PSA) b) a vacuum pressure swing adsorption (VPSA), c) a temperature swing adsorption (TSA) or These methods are known to the person skilled in the art and can be found in textbooks such as W. Käst, "Adsorption from the Gas Phase - Engineering Basics and Technical Processes", VCH Weinheim, 1988, Ruthven DM, S. Farooq, KS Knaebel, "Pressure Swing Adsorption", Wiley-VCH, New York-Chichester-Weinheim-Brisbane-Singapore-Toronto, 1994 or D. Bathen, M. Breitbach, "Adsorption Technique", Springer Verlag Berlin-Heidelberg, 2001, D. Basmadjian, "The Little Adsorption Book", CRC Press Boca Ronton, 1996 or publications such as A. Mersmann, B FiII, R. Hartmann, S. Maurer, Chem. Eng. Technol. 23/11 (2000) 937. The bed of an adsorber need not necessarily contain only a single adsorbent, but may consist of several layers of different materials. This can be used, for example, to sharpen the breakthrough front of the adsorbed species during the adsorption phase.

For example, a pressure swing adsorption for propane / propene T rennung be configured as follows: In four reactors operate in parallel in the following phases: In phase 1, an adsorber by supplying fresh gas, gas from a second adsorber in the adsorption mode or exhaust gas from a second adsorber , which is decompressed at the same time, brought to the working pressure (p _m a _x ι _m ai). In phase 2, the adsorbent is completely loaded with propene by further feed feed, preferably until the entire adsorption front has broken through and no more propene is adsorbed. In this case, a second reactor downstream in the adsorption mode is preferably switched on before breakthrough of the propene front. In Phase 3, the adsorber is purged with pure propene to displace non-adsorbed residual propane present in the adsorber. Rinsing may be in cocurrent or countercurrent, with direct current being preferred. The rinsing can be carried out at adsorption pressure. To save pure propene, however, a prior lowering of the adsorber pressure is preferred, particularly preferred is a similar propene partial pressure in the adsorption (phase 2) and purge phase (phase 3). The released at this pressure reduction gas mixture can be fed to another adsorber during phase 1 for pressure build-up. In phase 4, the loaded and purged adsorber is decompressed to recover the pure propylene stream. The product is preferably removed in countercurrent.

In addition, a negative pressure can be applied in phase 4. This embodiment is an example of a VPSA method.

To compensate for the temperature effects due to the adsorption heat / desorption cold, the supply or removal of heat may be advantageous. The heat input can take place in different ways: Conductively via internal heat exchangers, convectively via external heat exchangers or by radiation, for example by irradiation of micro or radio waves. Likewise, a heat input exceeding the desorption cooling compensation can be used to further facilitate desorption of the propene during phase 4. One Such process is a combination of pressure swing and thermal swing adsorption.

Desorption of the desired product can also be effected by displacement with an auxiliary component, for example N ₂ , CO ₂ or water vapor. It is exploited that the auxiliary component lowers the partial pressure of the propylene in the gas phase, while the absolute pressure can remain constant. In addition, a more strongly adsorbing auxiliary component, such as steam or CO ₂ , may also result in displacement of the product of value from the surface of the adsorbent. In the latter case, however, the auxiliary component must be removed in a further step from the surface of the adsorbent, z. B. by raising the temperature. Here, for example, temperature levels can be set, which lead in the presence of propylene to undesirable side reactions such as polymerization. Since in such a driving mode the excipient can get into the desorbed, a separation step, for. Example, by condensation, adsorption, separation via a membrane, distillation or by selective washing, connect.

The phases do not necessarily have the same length, so that a smaller or larger number of adsorbers can be used for synchronization.

If the desorbed propene does not have the desired degree of purity, a further purification, preferably adsorptive, can follow, in which case another adsorbent can also be used.

The adsorption is generally carried out at a temperature in the range of -50 to 250 ° C, preferably -10 to 90 ° C and particularly preferably 0 to 80 ° C. Further more preferably, the adsorption is carried out at a temperature in the range of 10 to 70 ° C, especially at 20 to 60 ° C and most preferably at 30 to 50 ° C.

The adsorption takes place at a pressure of generally from 1 to 40 bar, preferably from 1.5 to 20 bar, more preferably from 2 to 15 bar and in particular from 2.5 to 10 bar. Most preferably, the adsorption is carried out at a pressure in the range of 2.5 to 5 bar.

The desorption phase itself can be done both by reducing the pressure and by heat input as well as by a combination of both measures. The pressure reduction is preferably carried out to a pressure of less than 2.5 bar, in particular less than 2 bar. The specified pressure values represent absolute values.

The adsorption / desorption can be designed as a fixed bed, fluidized bed or moving bed process. Suitable apparatus are, for example, fixed bed reactors, rotary adsorbers or venetian blind filters. A detailed description of possible apparatus can be found in: Werner Käst, "Adsorption from the Gas Phase", VCH (Weinheim), H. Brauer, "The Adsorption Technique an Area with a Future", Chem.-Ing. Tech 57 (1985) 8, 650-653; Dieter Bathen, Marc Breitbach "adsorption technology", VDI book, 2001.

For desorption of adsorbed on the adsorbent gases, this is heated and / or relaxed to a lower pressure.

Preferably, according to the process for the technical production of propene according to the invention, the released propene can be obtained with a purity of more than 95% by volume with respect to the sum of the proportions by volume of propane and propene. More preferably, the purity is more than 99% by volume, in particular at least 99.5% by volume (polymer grade).

Another object of the present invention is the use of a porous organometallic framework material containing at least one coordinated to at least one metal ion, at least bidentate organic compound for the technical production of propene from a gas stream containing at least propane and propylene.

Examples

Example 1: Separation on Cu-BTC

193 g of I .S.δ-Cu-benzenetricarboxylic acid MOF (1.5 mm extrudates) are incorporated into a tubular reactor. Subsequently, the desired adsorption pressure is established with pure propane (various absolute pressures of 2.5-5 bar) and then converted to a mixture of about 50% propane and 50% propene (100 or 200 standard liters / h). The composition of the reactor exhaust gas is monitored by a mass spectrometer. First, the propene is adsorbed and only pure propane is detected. As soon as Propen breaks through, the trial ends. From the time to the first breakthrough, the propene capacity is calculated under the respective experimental conditions (see Table 1).

Subsequently, the sample is rinsed at room temperature with an increased amount of pure propane (about 100 Nl / h) for 30 min and started again with the pressure build-up for the next experiment. The following repeated separations also give the same values. Example 2: Separation on an Al-terephthalic acid MOF

212 g of an Al-terephthalic acid MOF (3 × 3 mm and 1.5 × 1.5 mm tablets) are treated analogously to Example 1.

Comparative Example 3: Separation on 4 Å molecular sieve

302 g of 4 Å molecular sieve (4-8 mesh) (strands 1.5 mm) are treated analogously to Example 1.

Comparative Example 4 Separation on 13X Molecular Sieve Analogously to Comparative Example 3, 13X molecular sieve (1.5 mm extrudates) is used.

Table 1

Example 5 An adsorber with a volume of about 0.2 l is filled with in each case different adsorbents in the activated state and these are additionally removed before the actual measurement in a warm nitrogen stream of residual moisture and adhering CO ₂ . For determining the separation capacity, the adsorber is first purged with pure propane at room temperature in a pressureless state for 15 minutes, and then the pressure in the system is increased to 5 bar. The pressure regulation takes place via downstream needle valves. Subsequently, the mixture is switched to a propane / propene mixture (GC analysis: 54.7% propene, 44% propane, balance N ₂ , flow 16 Nl / h) and the concentration profile at adsorber inlet or outlet is monitored by means of an IR gas cell , The propene capacity is calculated until the time when a significant increase in the propene signal is recorded for the first time. The results are summarized in Table 2.

Table 2

Fig. 1 shows the time course of the IR signal for propene (breakthrough curves). Here, the IR signal [a.u.] is plotted as a function of time t (in min.).

The adsorbents of Table 2 are as shown in Fig. 1 assigned to the individual curves.

Example 6:

In further experiments, propene was adsorptively separated from a gas mixture, which comes very close to the real composition of a product stream from the propane dehydrogenation.

The adsorbent used was Cu-BTC-MOF in the form of 1.5 mm strands.

The gas mixture is composed as follows: about 1.5% ethane, about 1.5% ethene,

- about 2% carbon monoxide,

- about 2.5% methane

- about 30.8% propane

- about 30.8% propene - the remainder is hydrogen The tests were carried out in an adiabatic tubular reactor (length 2000 mm, inner diameter 35 mm), which is provided with a 10-fold step thermoelement. The feed of the reactor with fresh gas is volume-controlled from steel bottles. The pressure was regulated via a valve in the exhaust gas. The gas composition was determined with an online IR meter at the entrance and exit of the reactor.

Test Parameters:

Fresh gas: see FIG. 2 for test A and FIG. 3 for test B reactor pressure: 2.5 bar

Temperature: room temperature

The sorbent is freed overnight from any adhering water or CO ₂ with warm, dry nitrogen (about 50 ° C, 500 Nl / h) before each experiment.

Trial A:

In experiment A, the reactor was pressed with pure propane to 2.5 bar. During the adsorption of propane, a temperature rise of 50 K was measured. After the reactor had cooled back to room temperature, it was charged with the gas mixture.

Propene and ethane were fully adsorbed from the beginning. Furthermore, a large part of the ethylene and a small part of the carbon monoxide was adsorbed. Methane and propane flowed through the reactor unhindered. After approx. 10 min. Initially, the concentration of ethane in the exhaust gas jumped.

After approx. 56 min. began to increase the concentration of ethylene. Only later after 134 min. the breakthrough of propene occurred, so that its desorption is possible by desorption of the propene.

During the adsorption of the gas mixture, a temperature rise of 15 K was measured.

In Fig. 2, the concentrations of propane and propene and the course of flow and pressure are shown. Here, the gas concentration (%) and gas flow (Nl / h) c and the pressure p (bar) as a function of time t (min.) Is shown. Curve 1 corresponds to the Fresh gas flow, curve 2 of the propane concentration, curve 3 the pressure and curve 4 of the propene concentration.

Experiment B: In experiment B, the reactor was pressurized with nitrogen to 2.5 bar. Subsequently, the reactor was immediately charged with the gas mixture.

The entire gas mixture was first adsorbed, resulting in a slight pressure drop in the reactor. Therefore, the fresh gas flow was increased in stages to 300 Nl / h.

After approx. 25 min. first broke methane and carbon monoxide through at the reactor outlet and had after about 10 min. reached their input concentration again. Shortly afterwards, ethane, ethene and propane in the exhaust gas were measured almost simultaneously. Ethane and ethene reached after approx. 5 min. their input concentration. Only later after 50 min did the breakthrough of propene finally take place, so that its desorption is possible by desorption of propene.

Throughout the experiment, the reactor pressure fluctuated somewhat due to the strong adsorption. During the adsorption of the gas mixture, a temperature rise of 75 K was measured.

In Fig. 3, the concentrations of propane and propene and the course of flow and pressure are shown. Here, the gas concentration (%) and gas flow (Nl / h) c and the pressure p (bar) as a function of time t (min.) Is shown. Curve 1 corresponds to the fresh gas flow, curve 2 to the pressure, curve 3 of the propane concentration and curve 4 of the propene concentration.

Claims

claims

1. A process for the technical recovery of propene from a propene and at least one further hydrocarbon-containing gas stream, the steps containing

(A) bringing into contact the gas stream with an adsorbent containing a porous organometallic framework material containing at least one at least one at least one metal ion coordinate bound at least bidentate organic compound, wherein the adsorbent is loaded with propene, and

(b) releasing the propene from the propene loaded adsorbent.

2. The method according to claim 1, characterized in that the at least one further hydrocarbon is propane.

3. The method according to claim 1 or 2, characterized in that the gas stream 5 to 95 vol .-% propene based on the sum of the volume fractions of propene and the further hydrocarbon or other hydrocarbons in the gas stream.

4. The method according to any one of claims 1 to 3, characterized in that the gas stream is an optionally purified product stream from propene production.

5. The method according to claim 4, characterized in that the optionally purified product stream from a cracking process, a propane dehydrogenation, an olefin conversion or a methanol / dimethyl ether conversion to

Propene production or a mixture of streams of two or more of these Propenherstellungen comes.

6. The method according to claim 5, characterized in that the optionally purified product stream originates from a propane dehydrogenation for propene production.

7. The method according to any one of claims 1 to 6, characterized in that the adsorbent is in an adsorber.

8. The method according to claim 7, characterized in that the adsorber is part of an adsorber system comprising at least three adsorbers which operate out of phase.

9. The method according to claim 8, characterized in that the release of the Propens takes place in quasi-continuous driving.

10. The method according to any one of claims 1 to 9, characterized in that the release of the propene by changing at least one of the physical see parameters selected from the group consisting of pressure and temperature.

1 1. A method according to any one of claims 1 to 10, characterized in that the released propene has a purity of about 95 vol .-% with respect to the sum of the volume propene and the further hydrocarbon or other hydrocarbons.

12. The method according to any one of claims 1 to 1 1, characterized in that the bringing into contact at a temperature in the range of -50 to 250 ° C follows.

13. The method according to any one of claims 1 to 12, characterized in that bringing into contact at a pressure in the range of 1 to 40 bar (absolute).

14. The method according to any one of claims 1 to 13, characterized in that the at least one metal ion is selected from the group of metals consisting of Mg, Al, In, Cu, Zn, Fe, Ni, Co, Mn, Zr, Ti, Sc, Y, La and Ce.

15. The method according to any one of claims 1 to 14, characterized in that derives at least one at least bidentate organic compound of a di-, tri- or tetracarboxylic acid or its sulfur analogues.

16. The method according to any one of claims 1 to 15, characterized in that the organometallic framework material is present as a shaped body.

17. The method according to any one of claims 1 to 16, characterized in that the maximum of the pore diameter distribution is at least 0.4 nm.

8. Use of a porous organometallic framework material comprising at least one coordinated to at least one metal ion at least bidentate organic compound for the technical production of propene from a propene and at least one further hydrocarbon-containing gas stream.