BRPI0710208A2 - a process for obtaining propylene technically from a gas stream comprising propylene and at least one other hydrocarbon, and use of a porous metal organic structure - Google Patents

Abstract

PROCESS FOR OBTAINING PROPENE TECHNIQUES FROM A GAS CHAIN UNDERSTANDING PROPENE AND AT LEAST ANOTHER HYDROCARBONET, AND USE OF A POROUS METALLIC ORGANIC STRUCTURE The invention refers to a method for commercially obtaining a propane 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 structural metal-organic material containing at least one bidentate organic compound, which is coordinately linked to at least one metal ion, said adsorber being charged with propene; and (b) the propene is released from the adsorbent loaded with the propene. The invention further relates to the use of a porous metallic organic structure to commercially obtain propylene from a gas stream containing propene and at least one additional hydrocarbon.

Description

"PROCEDURE FOR OBTAINING PROPENE FROM A GAS CURRENT UNDERSTANDING PELOMEN AND ANOTHER HYDROCARBON, AND, USE OF A POROUS METAL ORGANIC FRAMEWORK"

The present invention relates to a process for obtaining propylene from a gas stream comprising propylene and at least another hydrocarbon and also the use of a porous organic metal structure for propylene isolation.

Propylene is an important valuable product which serves, for example, as a starting material for the production of polypropene.

Propylene, like its homologous olefins, occurs only in very small quantities in natural gas or crude oil. Their direct production by isolation from natural sources is therefore not of economic importance.

However, there are many industrial processes in which a mixture of, in particular, propane and propene is initially formed, for example propane dehydrogenation, fluid catalytic cracking or steam cracking, MTO (methanol in olefin) etc. In all processes it is therefore necessary to separate propylene from the hydrocarbon mixture. This also applies to propylene production by deolefin metathesis. This separation may be preceded by numerous purification steps.

A possible method of separation is distillation, but due in particular to similar boiling points of propane and propene (according to VDI-Warmeatlas 5.7 K at 1 bar; 6.1 K at 5 bar) and the high purity required. However, it requires a large number of theoretical plates and is correspondingly complicated and expensive.

One process that is superior to distillation for separating and isolating propylene is adsorption.

Classical adsorbents for the industrial isolation of propane gas mixtures comprising propene together with other hydrocarbons, in particular propane, are zeolites.

Such zeolite based processes are described by F. A. DaSilva et al, Int. Eng. Chem. Res. 40 (2001), 5758; Da Silva et al., AIChEJournal 47 (2001), 341-357 and C.A. Grande et al., Int. Eng. Chem. Res. 44 (2005), 8815-8829.

Despite the adsorbent systems known in the prior art, there is a need to provide improved processes employing alternative adsorbents. In particular, the high temperature required in pressure swing adsorption in the zeolites represents a problem. In addition, diffusion problems are known to occur with zeolites and they have a comparatively low specific surface area. In addition, "polymer grade" purity can be achieved by using these adsorbents only at very high cost (higher productivity (mol (H * m)) would be desirable). In addition, there is an incentive to carry out adsorption under pressure, since in this case expensive compression of the chain comprising propylene may be dispensed with. For example, propane dehydrogenations are performed in a low pressure range of 0.1 to 5 bar.

It is thus an object of the present invention to provide alternative sorbents which can be used in improved processes for industrial propylene isolation.

The objective is achieved by a process for the industrial propylene isolation of a gas stream comprising propylene and at least another hydrocarbon comprising the steps of

(a) contacting the gas stream with an adsorbent comprising a porous metallic organic structure, comprising at least one at least bidentate organic compound, coordinated with at least one metallic ion, resulting in the adsorbent becoming compropene charged,

(b) propylene release from the compropene charged adsorbent.

It has been found that the use of an organic metal-porous structure makes particularly efficient processes for industrial propylene isolation possible.

The proportion of propylene in the gas stream may have several values and is largely dependent on the gas stream source. However, propene proportion based on the sum of the parts by volume of propene and the additional hydrocarbon or other hydrocarbons comprised in the gas stream is of particular importance, especially in the presence of propane, since the separation of hydrocarbons, in particular propane and propene , represents the main problem. Other gas stream constituents may, if appropriate, be separated in a preceding step by using, if appropriate, other adsorbents in place of an organic porous metal structure. In addition, other methods such as distillation may also be used for this purpose.

In addition to propylene, the gas stream comprises at least one other hydrocarbon. A plurality of other hydrocarbons is typically included in addition. Depending on the source of the degass current, the at least one other hydrocarbon besides propylene may be of a different nature. Also, its content is generally dependent on the source of the gas stream.

In particular, the at least one hydrocarbon is propane.

Other hydrocarbons may be, in particular, C1 -C4 alkanes such as methane, ethane, propane, n-butane, i-butane, C2 -C4 alkenes such as ethene, 1-butene, 2-butene and C2 -C4 alkynes such as asetino, propine, 1-butino, 2-butino and also alenes. In addition, higher hydrocarbons may also be present in the degas mixture.

It is preferred that the gas stream comprises from 5 to 95% by volume of propylene, based on the sum of the volume proportions of propylene of the other hydrocarbon or other hydrocarbons of the gas stream.

The propylene ratio is more preferably from 10 to 95% by volume, even more preferably from 50 to 95% by volume, even more preferably from 70 to 95% by volume, in particular 90 to 95% by volume. In addition, it is preferred that the absolute propane content in the degas stream can assume these values.

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

Such product streams typically comprise propenejo with other homologous alkanes, in particular propane, and alkanes and also other gaseous constituents which, however, may be removed by simple purification steps. An example of such a constituent of a propylene product stream which may be suitably removed by means of a conventional desiccant or by compression and cooling condensation. Another example is carbon dioxide, which can be removed by simple gas purification. Other examples are ethane and alkenes, which can be selectively hydrogenated in advance.

The optionally purified product stream from propylene production may be a stream that originates from a decay (steam cracking or catalytic cracking) process, a propane dehydrogenation process, a methanol (Me-OH) / dimethyl-based petrochemicals production process. ether or an olefin transformation (olefin metathesis or cracking).

These processes are known from the prior art. A starting material for cracking processes may be naphtha or LPG (liquid oil gas). LPG comprises mainly propane and butanes.

Another starting material may be LNG (natural gas), which consists essentially of ethane, LPG and light naphtha.

Finally, naphtha itself is a possible starting material for producing propylene. About 15% by weight of naphtha is converted toopopene.

Naphtha is the starting material for steam cracking. The desired target product in naphtha cracking is generally ethine. In addition, relatively large amounts of C3 hydrocarbons are also formed. The variation in temperature and residence time ("crack severity") allows the product spectrum, ie the distribution through C2-, C3- and C4-olefins, to be adjusted. Typical temperatures are in the range of 800 to 1000 ° C. Steam dilution (thus "steam cracking") enables a favorable thermal distribution within the pipe and also, as a result of the decrease in partial pressure, which promotes cracking product formation. A typical composition of a current C3 separation product would be, for example, 90 to 96% propene, 3 to 7% propane, up to 3% in each case of propadiene and brine, and possibly also small amounts of other higher hydrocarbons. lower compounds such as methane, ethane, ethylene, cyclopropane, butanes, butenes and C5- and C6- hydrocarbons.

The second largest source of propylene is catalytic cracking, for which fluid catalytic cracking (FCC) is now commonly used and is in conventional refineries directed at fuel production via alkylation or condensation. Fluid catalytic cracking is performed using fine sand-like catalysts (eg aluminum silicates) which have a large surface area. Oiling to form olefins occurs at temperatures in the range of 500 to 600 ° C within a residence time of a few seconds. During the cracking process, the catalyst becomes charred. To regenerate the catalyst, it is continuously discharged from the effective reactor and regenerated outside by full burn. The energy released during burning is returned to the process.

As an alternative to cracking processes, an olefin metathesis may also be performed for propylene production. Here, ethylene and 2-butene may be reacted to form propene.

Finally, conversion of methanol or dimethyl ether also represents a more or less objective method of producing propene. Such reactions are also referred to as "methanol in olefins". These reactions through zeolites (ZSM-5 or SAPO) have the objective of producing peropene / ethylene along with traces of Cs + or propene / gasoline production.

In either case, propylene has to be completely separated from, among others, more or less large amounts of LPG.

A particularly preferred method of propylene production to produce an optionally purified product stream is propane dehydrogenation.

In a preferred embodiment of the present invention, the optionally purified product therefore originates from a cracking process, a propane dehydrogenation, a deolefin metathesis or a methanol conversion to propene production, particularly a propane dehydrogenation.

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

A preferred propane dehydrogenation process comprises the steps:

A) the supply of a feed gas stream comprising propane;

B) supplying the feed gas stream comprising propane and, if appropriate, steam and if appropriate a gas stream comprising oxygen, within a dehydrogenation zone and sub-propane to dehydrogenation in propylene, providing a product b stream comprising propane, propylene, methane, ethane, ethane, hydrogen, possibly carbon monoxide, carbon dioxide, water vapor and oxygen;

C) cooling the compressed product gas stream b, if appropriate, and separating water vapor by condensation, providing a product gas stream and exhausting water vapor.

In a first part A) of the process, a gas stream comprising propane a is provided. This generally comprises at least 80 vol% propane, preferably 90 vol% propane.

In addition, the propane-comprising feed gas stream further generally comprises butanes (n-butane, isobutane). Typical compositions of the feed gas stream comprising propane are described in DE-A 102 46 119 and DE-A 102 45 585. The feed gas stream comprising propane a is usually obtained from liquid petroleum gas (LPG).

In part B) of the process, the feed gas stream comprising propane is fed into a dehydrogenation zone and subjected to generally catalytic dehydrogenation.

Here, propane is partially dehydrogenated into propylene through an active dehydrogenation catalyst in a dehydrogenation reactor. In addition, hydrogen and small amounts of methane, ethane, ethylene and C / (hydrocarbons (n-butane, isobutane, butenes, butadiene)) are obtained.

Carbon oxides (CO, CO2), in particular CO2, water vapor and possibly small amounts of inert gases, are also generally present in the propanocatalytic dehydrogenation gas mixture. The dehydrogenation gas stream generally comprises water vapor, which was originally added to the dehydrogenation gas mixture and / or, in the case of dehydrogenation in the presence of oxygen (oxidative or non-oxidative), is formed on dehydrogenation. Inert gases (nitrogen) are introduced into the gas chain dehydrogenation zone comprising oxygen fed when adhesion hydrogenation is performed in the presence of oxygen if pure non-fed oxygen. If a gas comprising oxygen is fed, its oxygen content is generally at least 40% by volume, preferably at least 80% by volume, particularly preferably at least 90% by volume and is in particular pure technical grade oxygen having a oxygen content of at least 40%. > 99% in order to avoid an excessively high proportion of inert gas in the product gas mixture. In addition, only unreacted propane is present in the product gas mixture.

Propane dehydrogenation may in principle be performed on all reactor types known in the prior art. A comparatively comprehensive description of reactor types that are suitable for the purposes of the invention is given in "Catalytica (R) Studies Division, Oxidative Dehydrogenation and Alternative Dehydrogenation Processes" (Study No. 4192 OD, 1993, 430 Ferguson Drive, Mountain View, California, 94043-5272, USA).

Dehydrogenation can be performed as oxidative or non-oxidative dehydrogenation. Dehydrogenation may be performed isothermally or adiabatically. Dehydrogenation can be carried out catalytically in a fixed bed, moving bed or leitofluidized reactor.

The dehydrogenation of oxidative catalytic propane is preferably carried out autothermally. For this purpose, oxygen is additionally mixed within the propane dehydrogenation reaction gas mixture in at least one reaction zone and the hydrogen and / or hydrocarbon comprised in the least partially burnt reaction gas mixture as a result of at least part of the heat. required dehydrogenation is generated directly in the reaction gas mixture in at least one reaction zone.

One aspect of the non-oxidative mode of operation compared to an oxidative mode of operation is at least the intermediate formation of hydrogen, which is present in the presence of hydrogen in the dehydrogenation gas.

A suitable type of reactor is a fixed bed tube reactor or jacket and tube reactor. In these, the catalyst (dehydrogenation catalyst and, if appropriate, specific oxidation catalyst) is present as a fixed bed in a reaction tube or a bundle of reaction tubes. Typical reaction tube diameters are about 10 to 15 cm. A typical jacket and tube dehydrogenation reactor comprises from about 300 to 1000 reaction tubes. The temperature inside the tubes is usually in the range of 300 to 1200 ° C, preferably in the range of 500 to 1000 ° C. Working pressure is usually 0.5 to 8 bar, often 1 to 2 bar when low vapor dilution is used, but may also be 3 to 8 bar when high vapor dilution is used (corresponding to the "active reform process"). (STAR process) or the Linde process) for propane or butane adhesion hydrogenation from Phillips Petroleum Co. Typical catalyst space speeds (GHSV) are from 500 to 2000 h "1, based on the hydrocarbon used. eg, spherical or cylindrical (hollow or solid).

Catalytic propane dehydrogenation may also, corresponding to the SnamprogettiArarsintez-FBD process, be performed in the presence of a heterogeneous catalyst in a fluidized bed. It is advantageous to operate two fluidized beds in parallel, with one of them generally being in the regeneration state. The working pressure is typically 1 to 2 bar and the dehydrogenation temperature is generally 550 to 600 ° C. The heat required for dehydrogenation may be introduced into the dewatering system by preheating the dehydrogenation catalyst to the dewatering temperature. Mixing a coalition comprising oxygen enables the preheaters to be partially dispensed, with the necessary heat generated directly in the reactor system by combustion of hydrogen and / or hydrocarbons in the presence of oxygen. If appropriate, a coalition comprising hydrogen may be further mixed.

Catalytic propane dehydrogenation can be performed in a tray reactor. If dehydrogenation is performed automatically with introduction of a gas stream comprising oxygen, it is preferably performed in a tray reactor. This comprises one or more successive catalyst beds. The number of catalyst beds may be from 1 to 20, advantageously from 1 to 6, preferably from 1 to 4, and in particular from 1 to 3. The reaction gas preferably flows radially or axially through the catalyst beds. In general, such a tray reactor is operated using a fixed catalyst bed. In the simplest case, the fixed catalyst beds are arranged axially in a bowl furnace reactor or in the concentricly arranged cylindrical mesh ring spans. A cup oven reactor corresponds to a tray. The performance of dehydrogenation in a single bowl furnace reactor corresponds to one embodiment. In another preferred embodiment, dehydrogenation is performed using 3 catalyst beds in a tray reactor.

In general, the amount of oxygen-comprising gas added to the reaction gas mixture will be selected such that the amount of heat required for propane dehydrogenation is generated by the combustion of hydrogen present in the reaction gas mixture and possibly hydrocarbons present in the mixture. of reaction gas and / or carbon present as carbon deposits. In general, the total amount of oxygen introduced based on the total amount of propane is from 0.001 to 0.8 mol / mol, preferably from 0.001 to 0.6 mol / mol, particularly preferably from 0.01 to 0.5 mol. / mol. Oxygen may be used as oxygen oxygen or as a gas comprising oxygen comprising inert gases.

However, in order to avoid high propane and propylene losses in the preparation (see below), it is essential that the oxygen content of the gas comprising oxygen used is high and at least 40% by volume, preferably at least 80% by volume. particularly preferable at least 90% by volume. A particularly preferred oxygen-comprising gas is pure technical grade oxygen having an O 2 content of about 99% by volume.

Hydrogen burned to generate heat is hydrogen formed in the dehydrogenation of catalytic propane and, if appropriate, hydrogen, which is additionally added as hydrogen comprising gas to the reaction gas mixture. The amount of hydrogen present should preferably be such that the molar ratio of H2 / O2 in the reaction gas mixture immediately after oxygen introduction is 1 to 10 mol / mol, preferably 2 to 5 mol / mol. In the case of multistage reactors, this applies to each intermediate introduction of gas comprising oxygen and, if appropriate, gas comprising hydrogen.

Hydrogen combustion occurs catalytically. The commonly used dehydrogenation catalyst also catalyzes the combustion of hydrocarbons and hydrogen with oxygen, so that, in principle, no specific oxidation catalyst other than this is required. In one embodiment, one or more oxidation catalysts that selectively catalyze the combustion of hydrogen as oxygen in the presence of hydrocarbons is / are employed. Combustion of these hydrocarbons with oxygen to form CO, CO2 and water then occurs only to a small extent. The dehydrogenation catalyst and oxidation catalyst are preferably present in different reaction zones.

In the case of a multistage reaction mode, the oxidation catalyst may be present in only one reaction zone, in a plurality of reaction zones or in all reaction zones.

The catalyst which selectively catalyzes the oxidation of hydrogen is preferably located where the prevailing oxygen partial pressures are higher than elsewhere in the reactor, particularly in the vicinity of the feed point for oxygen-comprising gas. The introduction of oxygen-comprising gas and / or hydrogen-comprising gas may be carried out at one or more reactor sites.

In one embodiment of the process of the invention, an intermediate introduction of gas comprising oxygen and gas comprising hydrogen is performed prior to each tray of a flaring reactor. In another preferred embodiment of the invention process, the introduction of oxygen-comprising gas and hydrogen-comprising gas is performed prior to each tray except the first tray. In one embodiment, a layer of a specific oxidation catalyst, followed by a layer of the dehydrogenation catalyst, is present downstream of each point of introduction. In another embodiment, no specific oxidation catalyst is present. The dehydrogenation temperature is generally from 400 to 1100 ° C and the pressure of the last tray reactor catalyst bed is generally 0.2 to 15 bar, preferably from 1 to 10 bar, particularly preferably from 1 to 5 bar. The special speed (GHSV) is generally from 500 to 2000 h "1, in high load operation also up to 100,000 h" 1, preferably from 4000 to 16 000 h ". A preferred catalyst that selectively catalyzes the hydrogen accumulation comprises oxides and / or Phosphates selected from the group consisting of the germanium, tin, lead, arsenic, antimony and bismuth oxides and phosphates.Another preferred catalyst catalyzing hydrogen accumulation comprises a noble metal of the transition group VIII and / or I.

The commonly used dehydrogenation catalysts comprise a support and an active composition. The support generally comprises a heat resistant oxide or mixed oxide. The dehydrogenation catalysts preferably comprise a selected metals oxide from the group consisting of zirconium dioxide, aluminum oxide, zinc oxide, silicon dioxide, titanium dioxide, magnesium oxide, lanthanum oxide, cerium oxide and mixtures thereof as a support. The mixtures may be physical mixtures or chemical mixed phases, such as mixed oxides, such as magnesium aluminum oxide or zinc aluminum oxide. Preferred supports are zirconium dioxide and / or silicon dioxide and particular preference is given to zirconium dioxide mixtures. and desilicon dioxide.

Suitable geometries of extruded shaped catalyst bodies, stars, rings, saddles, spheres, foams and monoliths have characteristic dimensions of 1 to 100 mm.

The active composition of the dehydrogenation catalysts generally comprises one or more members of the transition group VIII, preferably platinum and / or palladium, particularly preferably platinum. In addition, the dehydrogenation catalysts may comprise one or more of the major group I and / or II elements, preferably potassium and / or cesium. In addition, the dehydrogenation catalysts may comprise one or more elements of the transition group III, including the acetaminid lanthanides, preferably lanthanum and / or cerium. Finally, the dehydrogenation catalysts may comprise one or more elements of the main group III and / or IV, preferably one or more elements of the group consisting of boron, gallium, silicon, germanium, tin and lead, particularly preferably tin.

In a preferred embodiment, the dehydrogenation catalyst comprises at least one element of the transition group VII, at least one element of the main group I and / or II, at least one element of the main group III and / or IV and at least one element of the transition group. transition group III, including lanthanides and actinides.

For example, all the dehydrogenation catalysts described in WO 99/46039, US 4.88.372, EP-A 705 136, WO99 / 29420, US 5,220,091, US 5,430,220, US 5,877,369, EP may be used. 0 117 146, DE-A199 37 106, DE-A 199 37 105 and DE-A 199 37 107 for purposes of the invention. Particularly preferred catalysts are the catalysts of Examples 1,2, 3 and 4 of DE-A 199 37 107 .

Dehydrogenation of autothermal propane is preferably carried out in the presence of vapor. The added steam serves as a heat transfer medium and assists in the gasification of organic deposits in catalysts, as a result of which the carbonization of the catalysts opposes the operating life of the catalysts is increased. Here the organic deposits are converted to carbon monoxide, carbon dioxide and possibly water. Steam dilution increases equilibrium conversion.

The dehydrogenation catalyst may be regenerated in a manner known per se. Thus, steam may be added to the reaction gas mixture or a gas comprising oxygen may be passed through the catalyst doleite at elevated temperature from time to time and the carbon dioxide may be completely burned. If appropriate, the catalyst is reduced by a gas comprising hydrogen after regeneration.

The gas stream product b can be divided into two currents, one of which is recirculated for autothermal dehydrogenation, according to the DE-A 102 11 275 and DE-A100 28 582 gas recycling mode.

Propane dehydrogenation may be performed as oxidative dehydrogenation. Oxidative propane dehydrogenation can be performed as a homogeneous oxidative dehydrogenation or as a homogeneously catalyzed oxidative dehydrogenation.

If propane dehydrogenation is configured as a homogeneous deoxygenation for the purposes of the present invention, it may be carried out as described in US-A 3,798,283, CN-A1.105.352, Applied Catalysis, 70 (2), 1991, p. 175 to 187, Catalysis Today 13, 1991, pgs. 673 to 678 and prior patent application DE-A 1 96 22 331.

The temperature of homogeneous oxidehydrogenation is generally from 300 to 700 ° C, preferably from 400 to 600 ° C, particularly preferably from 400 to 500 ° C. The pressure can be from 0.5 to 100 bar or from 1 to 50 bar. It will often be from 1 to 20 bar, in particular from 1 to 10 bar.

The residence time of the reaction gas mixture under oxidehydrogenation conditions is usually from 0.1 to 0.5 to 20 seconds, preferably from 0.1 or 0.5 to 5 seconds. As a reactor, it is possible to use, for example, a tube furnace or a jacket and tube reactor, for example a countercurrent pipe furnace, using flue gas as a heat transfer medium or a jacket reactor. using a salt fusion as a heat transfer medium.

The propane to oxygen ratio of the starting mixture to be used may be from 0.5: 1 to 40: 1. The molar ratio of propane to molecular oxygen of the starting mixture is preferably <6: 1, more preferably <5: 1. In general, the aforementioned ratio will be> 1: 1, for example> 2: 1. The starting mixture may further comprise essentially inert constituents such as H2O, CO2, CO, N2, noble gases and / or propylene. propene may be comprised in fraction C3 from the refinery. Advantageous homogeneous oxidative dehydrogenation of propane in propenosis The ratio of the surface area of the reaction space to the volume of the reaction space is as small as possible since the homogeneous oxidative propane hydrogenation proceeds by a free radical mechanism and the surface. of the generally current reaction space as a free radical purifier. Particularly advantageous surface materials are aluminum oxides, fused silica, borosilicates, stainless steel and aluminum.

If the first reaction stage is configured as a heterogeneously catalyzed oxidehydrogenation for the purposes of the invention process, it can in principle be performed as described in USA 4,788,371, CN-A 1,073,893, Catalysts Letters 23 (1994) 103 - 106. W Zhang, Gaodeng Xuexiao Huaxue Xuebao, 14 (1993) 566, Z. Huang, ShiyouHuagong, 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-A 4,341,664, J. of Catalysis 167,560-569 (1997), J. of Catalysis 167, 5509-559 (1997), Topics in Catalysis 3 (1996) 265 275, US-A 5,086,032, Catalysis Letters 10 (1991) 181-192, Ind. Eng. Chem. Res. 1996, 35, 14-18, US-A 4,255,284, Applied CatalysisA: General, 100 (1993) 111-130, J. of Catalysis 148, 56-67 (1994), V.Cortês Corberán and S. Vic Bellón (Editors), New Developments in Selective Oxidation II, 1994, Elsevier Science BV, p. 305-313, 3rd World Congresson Oxidation Catalystis R.K. Grasselli, S.T. Oyama, A.M. Gaffney and J.E. (Editors), 1997, Elsevier Science B.V., pgs. 375 secs In particular, all oxidehydrogenation catalysts mentioned in the above documents may be used. What has been said regarding the above documents also applies to:

i) Otsuka, K .; Uragami, Y .; Komatsu, T .; Hatano, M. in Natural Gas Conversion, Stud. Surf Know. Catai .; Holmen A., Jens, K.-J.; Kolboe, S. Eds .; Elsevier Science: Amsterdam, 1991; Vol. 61, p. 15;

ii) Sesham, K. Swaan, H.M .: Smits, R.H.H .; van Ommen, J.G., Ross, J.R.H. in New Developments in Selective Oxidation; Stud. Surf Know.Catai .; Centi, G .; Trifiro, 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., I know. Catai .; Ruiz, P .; Delmon, B., Eds .; Elsevier Science: Amsterdam, 1991a; Vol. 72, p. 221;

iv) Smits, R.H.H .; Seshan, K .; Ross, J.R.H. Proceedings,

Symposium on Catalytic Selective Oxidation, Washington DC; American Chemical Society: Washington, DC, 1991 b; 1121;

v) Mazzocchia, C.; Aboumrad, C .; Daigne, C .; Temesti, E.; Hermann, J.M .; Thomas, G. Catai. Lett. 1991, 10, 181;

vi) Bellusi, G .; Conti, G .; Perathonar, S .; Trifiro, F. Proceedings, Symposium on Catalytic Selective Oxidation, Washington, DC American Chemical Society: Washington, DC, 1991; p. 1242;

(vii) Ind. Eng. Chem. Res. 1996, 35, 2137-2143 and

(viii) Symposium on Heterogeneous Hydrocarbon Oxidation Presented before the Division of Petroleum Chemistry, Inc., 21st National Meeting, American Chemical Society New Orleans, LA, March 24 - 29,1996.

Particularly suitable oxideshydrogenation catalysts are the DE-A multimetal oxide or A catalyst compositions 1 97 53 817, with the multimetal oxide or catalyst A compositions specified as being preferred and being particularly advantageous. Thus, active compositions particularly are multimetal oxide compositions of formula I

<formula> formula see original document page 18 </formula> where

M1 = Co, Ni, Mg, Zn, Mn and / or Cu, M2 = W, V, Te, Nb, P, Cr, Fe, Sb, Ce, Sn and / or La, a = 0.5 to 1, 5, b = 0 to 0.5 and

χ = a number that is determined by the valence and frequency of elements other than oxygen in I.

Other suitable multimetal oxide compositions as oxideshydrogenation catalysts are mentioned below:

Mo-V-Te / Sb-Nb-0 multimetal oxide catalysts are described in EP-A 0 318 295, EP-I 0 529 853, EP-A 0 603 838, EP-A 0 608836, 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, among others, described in Ε. M. Thorsteinson, Τ. P. Wilson, F. G.Young, Ρ. H. Kasei, Journal of Catalysis 52 (1978), pages 116 to 132 and US 4,250,346 and EP-A 0 294 845.

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

In principle, suitable active compositions can be produced in a simple manner by producing a very finely dried, preferably finely divided mixture, corresponding to their stoichiometry of suitable sources of their components and calcining the mixture at temperatures of 450 to 1000 ° C. Calcination may be carried out under inert gas or under an oxidative atmosphere, such as air (mixture of gas and oxygen) or under a reducing atmosphere (eg mixture of gas, oxygen and NH3, CO and / or H2). Possible sources of the active multimetal oxide component components are oxides and / or compounds that can be converted to oxides by heating, at least in the presence of oxygen. Except for the oxides, in particular, halides, nitrates, formates, oxalates, citrates, acetates, carbonates, deamine complex salts, ammonium salts and / or hydroxides may be used as starting compounds.

For purposes of the process of the invention, multimetal oxide compositions may be used in powder form or as shaped catalyst bodies having particular geometries, with the conformation being capable of being performed before or after final calcination. Suitable catalyst geometries are, for example, solid cylinders or hollow cylinders, having an outside diameter and a length of 2 to 10 mm. In the case of cylinders, a wall thickness of 1 to 3 mm is advantageous. Suitable hollow cylinder geometries are, for example, 7 mm χ 7 mm χ 4 mm or 5 mm χ 3 mm χ 2 mm or 5 mm χ 2 mm χ 2 mm (in each case length χ outer diameter χ inner diameter). Of course, all-active catalyst may also have a spherical geometry, with the ball diameter being able to fall from 2 to 10 mm.

Of course, the conformation of the active-pulverulent composition or its not yet calcined pulverulent precursor composition may also be accomplished by application to preformed inert catalyst supports. The layer thickness of the powder composition applied to the supporting body is advantageously in the range of 50 to 500 mm, preferably in the range 150 to 250 mm. Supporting materials may be aluminum oxides, silicon dioxide, thorium dioxide, zirconium dioxide, carbide or customary porous or non-porous silicon silicates such as magnesium silicate or aluminum silicate. The shaped bodies may have regular or irregular shapes, with regularly shaped support bodies having a distinct surface roughness, e.g. eg spheres, bold hollow cylinders having dimensions in the range of 1 to 100 mm, being preferred. The use of essentially non-porous spherical supports which are made of steatite and have a rough surface and a diameter of 1 to 8 mm, preferably 4 to 5 mm, is suitable.

The reaction temperature of the heterogeneously catalyzed propane oxideshydrogenation is generally from 300 to 600 ° C, usually from 350 to 500 ° C. The pressure is from 0.2 to 15 bar, preferably from 1 to 10 bar, for example from 1 to 5 bar. pressures above 1bar, p. from 1.5 to 10 bar, have been found to be particularly advantageous. In general, heterogeneously catalyzed propane oxidehydrogenation is carried out through a fixed catalyst bed. The latter is advantageously poured into the tubes of a jacket and tube reactor as described, for example, in EP-A 700 893 and EP-A 700 714 and also in the references cited herein. The average residence time of the reaction gas mixture in the catalyst bed is usually 0.5 to 20 seconds. The propane to oxygen ratio in the reaction gas starting mixture used for heterogeneously catalyzed propane oxidehydrogenation may, according to the invention, be 0.5: 1 to 40: 1. It is advantageous that the dopropane to molecular oxygen ratio of the starting gas mixture is <6: 1, preferably <5: 1. The aforementioned ratio will generally be> 1: 1, for example 2: 1. The starting gas mixture may further comprise essentially inert constituents such as H 2 O, CO 2, CO, N 2, noble gases and / or propylene. In addition, certain amounts of C1, C2 and C4 hydrocarbons may also be comprised.

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

Propane dehydrogenation provides a gaseous mixture which generally has the following composition: from 10 to 80% by volume of propane, from 5 to 50% by volume of propene, from 0 to 20% by volume of methane, C4 + ethane and hydrocarbons of 0 to 30% by volume of carbon oxides, 0 to 70% by volume of water vapor and 0 to 25% by volume of hydrogen and also 0 to 50% by volume of inert gases.

Preferred autothermal propane dehydrogenation provides a gaseous mixture which generally has the following composition: from 10 to 80% by volume of propane, from 5 to 50% by volume of propene, from 0 to 20% by volume of methane, ethane, ethylene and hydrocarbons -C4 +, from 0.1 to 30% by volume of carbon oxides, from 1 to 70% by volume of water vapor and from 0.1 to 25% by volume of hydrogen and also from 0 to 30% by volume inert gases.

In part C) of the process, water is first separated from the gas stream product b. Water is separated by condensation by cooling and, if appropriate, compressing the product gas stream may be carried out in one or more cooling and, if appropriate, stages of compression. In general, the product gas stream b is for this purpose cooled to a temperature in the range of from 20 to 80 ° C, preferably from 40 to 65 ° C. In addition, the product gas stream may be compressed, generally at a pressure in the range of 2 to 40 bar, preferably from 5 to 20 bar, particularly preferably from 10 to 20 bar.

In one embodiment of the process of the invention, the product b gas stream is passed through a cascade of heat exchangers and thus first cooled to a temperature in the range of 50 to 200 ° C and thereafter further cooled to a temperature. 40 to 80 ° C, for example 55 ° C, by water in a rapid cooling tower. Here, the main part of the water vapor condenses, accompanied by part of the C4 + hydrocarbons, in particular the C5 + hydrocarbons, comprised in the product gas stream b. Suitable heat exchangers are, for example, direct heat exchangers and countercurrent heat exchangers, e.g. eg gas-gas countercurrent heat exchangers and air coolers.

A product gas stream c, exhausted in water vapor, is obtained. It generally still comprises from 0 to 10% by volume of water vapor. In order to achieve virtually complete removal of water from the stream of product c, when using particular adsorbents in step D), drying may be provided by molecular sieves, in particular molecular sieves 3A, 4A, 13X or, preferably, oxides of aluminum or membranes.

Before step (a) of the process of the invention for obtaining propylene technique is carried out, carbon dioxide may be separated from the gas stream and by a gas wash or by absorption of solid absorbents. Carbon dioxide gas flushing may be preceded by a separate combustion stage in which carbon monoxide is selectively oxidized to carbon dioxide.

CO2 removal is generally carried out using sodium hydroxide solution, potassium hydroxide solution or a kanolamine solution as a purification liquid, preferably an activated N-methyl thiethanolamine solution. In general, the product gas stream c is compressed to a pressure in the range of 5 to 25 bar by single stage or multi stage compression prior to performing gas purification. A stream c is obtained which is carbon dioxide depleted and has a CO2 content of generally <1000 ppm, preferably <100 ppm, particularly preferably <20 ppm.

However, preference is given to CO2 separation by sorption in suitable solid sorbents, for example 13X molecular sieve, calcium oxide, barium oxide, magnesium oxide or hydrotalcites.

In a particularly preferred embodiment, the purified product chain obtained in this manner from propylene production represents the gas stream comprising at least propane and propylene, which is used in the process of the invention for the industrial isolation of propylene.

The porous metal organic structure comprises at least one at least bidentate organic compound coordinated with at least one metal ion. This organic metal structure (MOF) is, for example, described in US 5,648,508, EP-AO 790 253, MO Keeffe et al, J. Sol. StateChem., 152 (2000), pages 3 to 20, H. Li et al., Nature 402 (1999), page 276, M. Eddaoudi et al, Topics in Catalysis 9 (1999), pages 105 to 111, B. Cheneal., Science 291 (2001), pages 1021 to 1023 and DE-A-101 11 230, WO-A2005 / 049892 and AC Sudik and al., J. Am. Chem. Sound. 127 (2005), 7110 to 7118.

The organic metal structures used in accordance with the present invention comprise pores, in particular micropores and / or mesopores. Micropores are defined as pores having a diameter of 2nm or less and mesopores are defined as a diameter in the range of 2 to 50 nm, in each case according to the definition given in Pure & AppliedChem. 57 (1985), 603 - 619 in particular on page 606. The presence of micropores and / or mesopores can be verified by desorption measurements, with these measurements determining the absorption capacity of the 77 kelvin nitrogen MOF according to DIN 66131 and / or DEST 66134.

The specific surface area calculated according to the Langmuir model according to DrN 66135 (DIN 66131, 66134) of a powdery structure is preferably greater than 5 m2 / g, more preferably 20 than 10 m / g. g, more preferably greater than 50 m / g, even more preferably greater than 500 m / g, even more preferably greater than 1000 ra / g and particularly preferably greater than 1500 m2 / g.

The shaped MOF bodies have a smaller surface area, but preferably greater than 10 m2 / g, more preferably greater than 50 m / g, even more preferably greater than 500 m / g, in particular greater than 1000 m / g. .

For the purposes of the present invention, the maximum pore diameter distribution should be at least 4 µm. This maximum is preferably in the range of 4.3 to 20 Â. Particular preference is given to band 5 to 13 Á.

The metal components of the structure used in accordance with the present invention are preferably selected from groups Ia, IIa, IIIa, IVa to VIIIa and Ib to VIb. Other preference is given to groups IIa, IIIb, IIIa aVIa of the Periodic Table of the Elements and also to lanthanides, V, Mn, Fe, Ni, Co. Particular preference is given to Mg, Ca, Sr, Ba, Sc, Y, Ti. , Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ro5 Os, Co, Rh, Go, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Hg, AI, Ga, In, T1, Si, Ge, Sn, Pb, As, Sb and Bi. Even greater preference is given to Mg, AI, In, Cu, Zn, Fe, Ni, Co, Mn, Zr, Ti, Sc, Y, La, Ce. Most preference is given to Mg, AI, In, Cu, Zn, Fe, Zr, Y. In the case of copper, preference is given to types of MOF that do not have Culivre's coordinating site.

With respect to the ions of these elements, particular mention may be made of Mg2 +, Ca2 +, Sr2 +, Ba2 +, Sc3 +, Y3 +, Ti4 +, Zr4 +, V4 +, V3 +, V2 +, N3, Cr3 +, Mo3 +, M3 +, Mn2 +, Mn2 +, Mn2 +, Mn2 +, Mn2 +, Mn2 +, Mn2 + Re3 +, Re2 +, Fe3 +, Fe2 +, Ru3 +, Ru2 +, Os3 +, Os2 +, Co3 +, Co2 +, Rh2 +, Rh +, Ir2 +, Ir +, Ni2 +, Ni +, Pd2 +, Pd +, Pt +, Cu2 +, Cu +, Ag +, Au +, Zn2 + Cd2 +, Hg2 +, Al3 +, Ga3 +, In3 +, Tl3 +, Si4 +, Si4 +, Ge4 +, Ge4 +, Sn4 +, Pb4 +, Pb2 +, As5 +, As3 +, As +, Sb5 +, Sb3 +, S5 +, Bi3 + and Bi +.

The term "at least bidentate organic compound" refers to an organic compound comprising at least one functional group which is capable of forming at least two, preferably two coordinate bonds with a given metal ion and / or a coordinate bond with one of two or more. preferably two metal atoms.

As functional groups via which the mentioned coordinate bonds may be formed, mention may be made in particular of 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, -PO3H, -AsO3H, -AsO4H, -P (SH) 3, -As (SH) 3, -CH (RSH) 2, -C (RSH) 3 -CH (RNH2), -C (RNH2) 3, -CH (ROH) 2, -C (ROH) 3, - CH (RCN) 2, -C (RCN) 3, wherein R is preferably an alkylene group having 1, 2, 3, 4 or 5 carbon atoms, for example a methylene, ethylene, n-propylene, i-propylene group , n-butylene, i-butylene, tert-butylene or n-pentylene or an aryl group comprising 1 or 2 aromatic rings, for example, 2 C 6 rings which may be optionally fused and may be suitably substituted, independently of each other, by, in each case at least one substituent and / or may comprise, independently of each other, in each case at least one heteroatom, such as Ν, O and / or S. In equally preferred embodiments, mention may be made of and be made of functional groups wherein the abovementioned radical R is not present. Here mention may be made of, inter alia, -CH (SH) 2, -C (SH) 3, -CH (NH2) 2, -C (NH2) 3, -CH (OH) 2, -C (OH ) 3, -CH (CN) 2 or -C (CN) 3.At least two functional groups may in principle be attached to any suitable organic compound as long as it is ensured that the organic compound containing these functional groups is capable of forming coordinated allocation and produce the structure.

Organic compounds comprising at least two functional groups are preferably derived from an aliphatic or unsaturated compound or an aromatic compound or both an aliphatic and aromatic compound.

The aliphatic compound or the aliphatic part of both the aliphatic and aromatic compound may be linear and / or branched and / or cyclic, with a plurality of rings per compound also being possible. The aliphatic compound or the aliphatic part of both the aliphatic and aromatic compound most preferably comprises from 1 to 15, more preferably from 1 to 14, more preferably from 1 to 13, more preferably from 1 to 11, and particularly preferably from 1 to 11. 10 carbon atoms, for example 1,2, 3, 4, 5, 6, 7, 8, 9, or 10 carbon atoms. Particular preference is given herein to, among others, methane, adamantane, acetylene, ethylene or butadiene .

The aromatic compound or the aromatic part of both the aromatic and aliphatic compound may have one or more rings, for example two, three, four or five rings, with the rings being able to be present separately and / or at least two rings may be present in cast form. The particularly preferred aromatic or aromatic part of the aliphatic as well as aromatic compound has one, two or three rings, with one or two rings being particularly preferred. In addition, the rings of said compound may independently comprise at least one heteroatom such as N, O, S, Β, P, Si, Al, preferably Ν, O and / or S. The aromatic compound or aromatic part Both aromatic and aliphatic compounds most preferably comprise one or two C6 rings, both of which are present separately from each other or in fused form. Aromatic compounds deserving particular mention are benzene, naphthalene and / or biphenyl and / or bipyridyl and / or pyridyl.

For example, mention may be made of, among others, transmuconic acid or fumaric acid or phenylenebisacrylic acid.

The at least bidentate organic compound is preferably derived from a dicarboxylic, tricarboxylic or tetracarboxylic acid or a sulfur analog thereof. Sulfur analogues are the C (= 0) SH functional groups and their tautomer and C (= S) SH, which may be used in place of one or more carboxylic acid groups.

For purposes of the present invention, the term "is derived" means that the at least bidentate organic compound may be present in partially deprotonated or fully deprotonated form in the structure. In addition, the at least bidentate organic compound may comprise other substituents such as -OH, -. NH 2, -OCH 3, -CH 3, -NH (CH 3), -N (CH 3) 2, -CN and halides.

For purposes of the present invention, mention may be made for example of dicarboxylic acids such as oxalic acid, succinic acid, tartaric acid, 1,4-butanedicarboxylic acid, 4-oxopyran-2,6-dicarboxylic acid, 1,6-hexanedicarboxylic acid decanedicarboxylic acid, 1,8-heptadecanedicarboxylic acid, 1,9-heptadecanedicarboxylic acid, heptadecanedicarboxylic acid, acetylenedicarboxylic acid, 1,2-benzenedicarboxylic acid, 2,3-pyridinedicarboxylic acid, pyridine-2,3-dicarboxylic acid, 1, 3-Butadiene-1,4-dicarboxylic acid, 1,4-benzene dicarboxylic acid, p-benzenedicarboxylic acid, imidazole-2,4-dicarboxylic acid, 2-methylquinoline-3,4-dicarboxylic acid, quinoline-2,4 -dicarboxylic acid, quinoxaline-2,3-dicarboxylic acid, 6-chloroquinoxaline-2,3-dicarboxylic acid, 4,4-diamino-phenylmethane-3,3'-dicarboxylic acid, quinoline-3,4-dicarboxylic acid, 7- chloro-4-hydroxyquinoline-2,8-dicarboxylic acid di imidodicarboxylic acid, pyridine-2,4-dicarboxylic acid, 2-methylimidazol-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-dioxaoctanodicarboxylic acid, 3,5-cyclohexadiene-1,2-dicarboxylic acid, octanodicarboxylic acid, pentane-3,3-dicarboxylic acid 4,4'-diamino-1,1'-biphenyl-3,3'-dicarboxylic acid, 4,4'-diaminobiphenyl-3,3'-dicarboxylic acid, benzidine-3,31-dicarboxylic acid, 1, 4-bis (phenylamino) benzene-2,5-dicarboxylic acid, 1,1'-binfatyl-5,5'-dicarboxylic acid, 7-chloro-8-methylquinoline-2,3-dicarboxylic acid, 1-anilinoanthraquinono-, 2,4'-dicarboxylic acid, polytetrahydrofuran-250-dicarboxylic acid, 1,4-bis (carboxymethyl) piperazine-2,3-dicarboxylic acid, 7-chloro-quinoline-3,8-dicarboxylic acid, 1- (4-carboxy) ) phenyl-3- (4-chloro) phenylp irazoline-4,5-dicarboxylic acid, 1,4,5,6,7,7-hexachloro-5-norbornene-2,3-dicarboxylic acid, phenylindanedicarboxylic acid, 1,3-dibenzyl-2-oxoimidazolidine-4,5 dicarboxylic acid 1,4-

cyclohexanedicarboxylic acid, phthalene-1,8-dicarboxylic acid, 2-benzoylbenzene-1,3-dicarboxylic acid, 1,3-dibenzyl-2-oxoimidazolidine-4,5-cis-dicarboxylic acid, 2,2'-bikinolinic acid 4,4-dicarboxylic acid, pyridine-3,4-dicarboxylic acid, 3,6,9-trioxaundecanedicarboxylic acid, O-hydroxybenzophenonodicarboxylic acid, Pluriol E 300-dicarboxylic acid, Pluriol E400 - dicarboxylic acid, Pluriol E 600-dicarboxylic acid, pyrazole acid -3,4-dicarboxylic acid, 2,3-pyrazinodicarboxylic acid, 5,6-dimethyl-2,3-pyrazinodicarboxylic acid, 4,4-diamino (diphenyl ether) diimidodicarboxylic acid, 4,4'-diaminodiphenylmethanediimidate dicarboxylic acid, 4 , 4'-diamino (diphenyl sulfono) diimidodicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,3-adamantane dicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 8-methoxy-2,3 acid -naphthalenedicarboxylic acid, 8-nitro-2,3-naphthalenedicarboxylic acid, 8-sulfo-2,3-naphthalenodic acid icarboxylic 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 (1H) -oxythiochromene-2,8-dicarboxylic acid, 5-tert-butyl-1,3-benzenedicarboxylic acid, 7,8-quinolinodicarboxylic acid, 4,5-imidazol-dicarboxylic acid, 4-cyclohexenecarboxylic acid 1,2-dicarboxylic acid, hexatriacontanedicarboxylic acid, tetradecanedicarboxylic acid, 1,7-heptanedicarboxylic acid, 5-hydroxy-1,3-benzenedicarboxylic acid, pyrazine-2,3-dicarboxylic acid, furan-2,5-dicarboxylic acid, nonene-6,9-dicarboxylic acid, eicosenedicarboxylic 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-dichlorofluororubin-4,11-dicarboxylic acid, 7-chloro-3-methyl-quinoline-6,8-dicarboxylic acid, 2,4-dichlor obenzenophenone-2 ', 5'-dicarboxylic acid, 1,3-benzenedicarboxylic acid, 2,6-pyridinedicarboxylic acid, 1-methylpyrrol-3,4-dicarboxylic acid, 1-benzyl-1H-pyrrol-3,4-dicarboxylic acid, anthraquinone-1,5-dicarboxylic acid, 3,5-pyrazoldicarboxylic acid, 2-nitrobenzene-1,4-dicarboxylic acid, heptane-1,7-dicarboxylic acid, 1,3-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 -quinolinotricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-btanotricarboxylic acid, 2-phosphono-1,2,4-butanotricarboxylic acid, 1,3,5-benzenotricarboxylic acid, 1-hydroxy-1, 2,3-propanetricarboxylic acid 4,5-dihydro-4,5-dioxo-1H-pyrrolo [1,3-F] quinoline-2,7,9-tricarboxylic acid 5-acetyl-3-amino-6- methylbenzene-1,2,4-tricarboxylic acid 3-amino-5-b enzoyl-6-methylbenzene-1,2,4-tricarboxylic acid, 1,2,3-propanetricarboxylic acid or aurintricarboxylic acid, or tetracarboxylic acids such as 1,1-dioxideperyl [1,12-BCD] thiophene-3,4,9, 10-tetraccharboxylic, perylenetetracarboxylic acids such as perylene-3,4,9,10-tetracarboxylic acid or (perylene 1,1-sulfone) -3,4,9,10-tetracarboxylic acids, butanotetracarboxylic acids such as 1,2 3,4-butanotetracarboxylic acid or meso-1,2,3,4-btanotetracboxylic acid, decane-2,4,6,8-tetracboxylic acid, 1,4,7,10,13,16-hexaoxacyclooctadecane-2,3 acid , 11,12-tetracarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid, 1,2,11,12-dodecanotetracarboxylic acid, 1,2,5,6-hexanotetracrboxylic acid, 1,2,7,8-octane tetracarboxylic acid, 1,4,5-8-naphthalenetetracarboxylic acid, 1,2,9,10-decanotetracarboxylic acid, benzophenonotetracarboxylic acid, 3,3 ', 4,4'-benzophenonotetracarboxylic acid, tetrahydroantetracarboxylic acid or cyclops acids nanotetracarboxylic acids, such as cyclocyclopentane-1,2,3,4-tetracarboxylic acid.

Very particular preference is given to the optional use of monosubstituted aromatic dicarboxylic, tricarboxylic or tetracarboxylic acids having one, two, three, four or more rings, with each ring being capable of comprising at least one heteroatom and two or more rings capable of comprising identical or different heteroatoms. . For example, preference is given to dicarboxílicosmonocíclicos acids, monocyclic citric acid, tetracarboxílicosmonocíclicos acids, bicyclic dicarboxylic acids, tricarboxílicosbicíclicos acids, bicyclic tetracarboxylic acids, tricyclic dicarboxylic acids, tricyclic tricarboxylic acids, tricyclic tetracarboxylic acids, ácidosdicarboxílicos tetracyclic tetracyclic tricarboxylic acids and / or ácidostetracarboxílicos tetracyclic. Suitable heteroatoms are, for example, N, O, S, Β, P, Si, Al and preferred heteroatoms are N, S and / or O. A suitable substituent in this regard is, among others, -OH, a nitro group, a amino group or an alkyl or alkoxy group.

As at least bidentate organic compounds, particular preference is given to the use of acetylenedicarboxylic acid (ADC), benzenedicarboxylic acids, naphthalenedicarboxylic acids, biphenyldicarboxylic acids such as 4,4'-biphenyldicarboxylic acid (BPDC), bipyridinedicarboxylic 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), adamantanodibenzoate (ADB), benzenetribenzoate (BTB), methanotetrabenzoate (MTB), adamantanotetrazenzoate or dihydroxyterephthalic acids such as 2,5-dihydroxyterephthalic acid (DHBDC).

Particular preference is given to the use, inter alia, of isophthalic acid, terephthalic acid, 2,5-dihydroxyterephthalic acid, 1,2,3-benzenetricarboxylic acid, 1,3,5-benzene tricarboxylic acid, 2,2 'acid -bipyridine-5,5'-dicarboxylic acid, aminoterephthalic acid or diaminoterephthalic acid.

Except for these at least bidentate organic compounds, aMOF may also comprise one or more monodentate ligands. Suitable solvents for preparing the MOF include, but are not limited to, ethanol, dimethylformamide, toluene, methanol, chlorobenzene, diethylformamide, dimethyl sulfoxide, water, hydrogen peroxide, methylamine, sodium hydroxide solution, N-methylpyrrolidone ethers, acetonitrile, debenzyl chloride, triethylamine, ethylene glycol and mixtures thereof. Other metal ions, at least bidentate organic compounds and solvents for preparing asMOFs are described, among others, in US-A 5,648,508 or DE-A 101 11 230.

The size of the MOF product may be controlled by choosing the appropriate ligand and / or at least bidentate organic compounds. In general, the larger the organic compound, the larger the doporus size. The pore size is preferably from 0.2 nm to 30 nm, particularly preferably from 0.3 nm to 3 nm, based on the crystalline material.

However, larger pores whose size distribution could also occur in a conformed MOF body. However, preference is given to more than 50% of the total pore volume, in particular more than 75% being composed of pores having a pore diameter of up to 1000 nm. However, preference is given to a major portion of the pore volume being composed of pores of two diameter ranges. It is therefore preferred that more than 25% of the total pore volume, in particular more than 50% of the total pore volume, is composed of pores of a diameter range of 100 nm to 800 nm and more than 15% of the volume of pore. porototal, in particular more than 25% of the total pore volume is composed of pores with a diameter range up to 10 nm. Pore distribution can be determined by mercury porosimetry.

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

Metallic organic structures are generally used as shaped bodies, for example as irregular beds of spheres, rings, extruded or pellets or as orderly internals such as conditioning, honeycomb bodies and monoliths.

The production of shaped bodies is described, for example, in WO-A 03/102 000. Preference is given to the use of shaped body beds, which are very densely packed. The shaped bodies, therefore, preferably have a diameter at their narrowest point of no more than 3 mm, more preferably no more than 2 mm, most particularly preferably no more than 1.5 mm. Particular preference is given to pellet shaped bodies. An alternative is the installation in the form of a monolithic structure, since the gas stream can equally readily flow through the grand channels here, while the wall material is also very densely packed.

In step (a) of the process of the invention for industrial propylene isolation, complete separation of propylene from other gas constituents is not required. Preferably, the objective is very complete adsorbent filler with pure propene. Since the adsorbent coefficient of adsorption on the adsorbent is higher than that of the other gas constituents, other gas constituents are gradually displaced from the adsorption sites, so that in the end propylene is selectively adsorbed. This applies in particular to the propane present in the gas stream.

When the gas stream originates from de-hydrogenation of propane, the undercurrent comprising propane may be recirculated for propane adhesion hydrogenation.

The adsorbent is typically present in an adsorber. Except for the organic metal structure, the adsorbent or adsorber may comprise other adsorbents, such as molecular sieves or the like.

The absorber reactor is preferably part of an absorber system comprising at least three adsorbers that cooperate in displaced phases.

This makes it possible to perform propylene release in step (b) of the process of the invention for propylene isolation in a continuous mode of operation.

Propylene release in step (b) of the process of the invention for industrial propylene isolation is preferably accomplished by changing at least one of the selected physical parameters from the group consisting of pressure and temperature.

Preference is given to performing at least one pressure change.

Release by means of a pressure change can be accomplished by reducing the pressure until a vacuum is applied. However, for purposes of the present invention, a reduction in the partial pressure of the pressure is sufficient to release the latter. This can, for example, be accomplished by displacing the propene with inert gas, which can easily be separated again later.

Step (a) of the process of the invention for industrial propene isolation is an adsorption stage and step (b) of the invention process for industrial propene isolation is a desorption stage. If adsorption and desorption are then performed with a cyclic change in pressure and / or temperature, numerous possibilities for industrial implementation are known to those skilled in the art.

In all of these, at least two, preferably three, particularly preferably at least four adsorbers are operated in parallel and at least two, but preferably all of these operate in common phase shift relative to the respective other adsorbers.

Possible variants are a) a pressure swing adsorption (PSA), b) a vacuum pressure swing adsorption (VPSA), c) a temperature oscillating adsorption (TSA) or a combination of various processes. in principle, those skilled in the art and further details can be found in textbooks such as W. Kast, "Adsorption aus der Gasphase - Ingenieurwissenschaftliche Grundlagen undtechnische Verfahren", VCH WeinheIII, 1988, DM Ruthven, S. Farooq, KS Knaebel, Pressure Swing Adsorption, Wiley-VCH, New York-Chichester-Weinheim-Brisbane-Singapore-Toronto, 1994 or D. Bathen, M. Britbach, Adsorptionstechnik, Springer Verlag Berlin-Heidelberg, 2001, D. Basmadjian, "The Little Adsorption Book", CRC Press Boca Raton, 1996 or other publications such as A. Mersmann, B. Fill, R. Hartmann, S. Maurer, Chem. Eng. Technol. 23/11 (2000) 937. An adsorbent bed does not necessarily have to comprise a single adsorbent, but may instead consist of numerous layers of different materials. This can for example be used to sharpen the front of the adsorbed species during the adsorption phase.

For example, a pressure swing adsorption for propane / propene separation may be configured as follows: Four reactors operate in parallel in the following displacement phases: In phase 1, an adsorber is brought to operating pressure (Pmax) by introducing fresh gas. , gas from a second adsorber in the adsorption mode or gas released from a second adsorber which is at the same time compressed. In step 2, the adsorbent is fully charged with propylene by additional feed introduction, preferably until the entire adsorption front has penetrated and no further propylene is adsorbed. In this case, a second reactor is preferably switched downstream in the propene front penetration adsorption mode. In phase 3, the adsorber is flooded with pure propylene in order to displace unsorbed residual propane presentan adsorber. Flooding may be co-current or counter-current, with co-current being preferred. Flooding can be performed at adsorption pressure. However, earlier drop in sorbent pressure is preferred in order to save pure propylene; Particular preference is given to a similar propylene partial pressure in the deadsorption phase (phase 2) and the flood phase (phase 3). The gas mixture released at this pressure decrease may be fed to another adsorber during stage 1 to increase the pressure. In step 4, the charged and flooded adsorber is decompressed to obtain the pure propylene stream. The product is preferably discharged in counter current.

In addition, subatmospheric pressure can be applied at phase 4. This embodiment is an example of a VPSA process.

To compensate for temperature effects due to the heat of desorption / desorption cold, the introduction or removal of heat may be advantageous. Heat may be introduced in different ways: conductively via an internal heat exchanger, convectively via an external heat exchanger or by radiation, for example by microwave injection or radio waves. Also, a heat input going beyond desorption cold compensation can be used to further assist the propylene desorption during phase 4. Such a process represents a combination of a pressure swing adsorption and a temperature swing adsorption.

Desorption of the desired product may also be accomplished by displacement with an auxiliary component, for example N 2, CO 2 by vapor. Here, use is made of the fact that the auxiliary component decreases the partial pressure of propylene in the gas phase, while the absolute pressure may remain constant. In addition, a more strongly absorbed auxiliary component, for example water vapor or CO2, may also result in displacement of the desired product from the surface of the adsorbent. However, in this case the auxiliary component has to be removed from the sorbent surface in another step, e.g. eg by increasing the temperature. Here it is also possible, for example, to adjust the temperature levels, which, in the presence of propylene, results in undesirable side reactions such as polymerization. Since in such mode of operation the auxiliary can penetrate the desorbed gas, a separation step, e.g. e.g., by condensation, adsorption, membrane separation, distillation or selective purification may follow.

Phases do not necessarily have to be of the same duration, so that fewer or more adsorbers can also be used for synchronization.

If the desorbed propylene is not of the desired degree of purity, further purification, preferably by adsorption, may follow, with a different absorbent also being able to be used here.

Adsorption is generally carried out at a temperature in the range from -50 to 250 ° C, preferably from -10 to 90 ° C and particularly preferably from 0 to 80 ° C. In addition, adsorption is most preferably performed at a temperature in the range of 10 to 70 ° C, in particular from 20 to 600 ° C and most particularly preferably from 30 to 50 ° C.

Adsorption is generally carried out at a pressure of from 1 to 40 bar, preferably from 1.5 to 20 bar, particularly preferably from 2 to 15 bar and in particular from 2.5 to 10 bar. Adsorption is very particularly preferably carried out at a pressure in the range of 2.5 to 5 bar.

The desorption phase itself can be performed by lowering the pressure or introducing heat or by a combination of the two measures. In the event of a pressure decrease, the pressure is preferably decreased to a pressure of less than 2.5 bar, in particular. less than 2 bar.

The indicated pressure values are absolute values.

Adsorption / desorption can be configured as a fixed bed, fluidized bed or moving bed process. Suitable apparatus are, for example, fixed bed reactors, rotary adsorbers or Venetian filters. A comprehensive description of possible appliances can be found at: Werner Kást, "Adsorption aus der Gasphase", VCH (WeinheIII); H. Brauer, "Die Adsorptionstechnik in Gebiet mit Zukunft", Chem.-Ing. Tech 57 (1985) 8, 650-653; Dieter Bathen, Marc Breitbach "Adsorptionstechnik", VDI-book, 2001.

To desorb the adsorbed gases in the adsorbent, they are heated and / or depressurized at a lower pressure.

The process of the invention for industrial depropen insulation preferably enables propene to be released to be obtained in a purity of greater than 95% by volume, based on the sum of propane and propene volumes. Purity is more preferably greater than 99 vol%, in particular at least 99.5 vol% (grapolymer).

The present invention further provides the use of a porous metal organic structure comprising at least one less bidentate organic compound coordinated with at least one metal ion for industrial propylene isolation of a gas stream comprising at least propane and propylene.

Examples

Example 1: Cu-BTC Separation

193 g of 1,3,5-Cu-benzenetricarboxylic acid MOF (1.5 extruded) is installed in a tube reactor. The desired absorption pressure is subsequently established using pure propane (several absolute pressures in the range 2.5 - 5 bar) and the feed is then changed to a mixture of about 50% propane and 50% propene (100 or 200 standard liters). /H). The composition of the reactor off-gas is monitored by means of a mass spectrometer. Initially, propene is adsorbed and only pure propane is detected. As soon as propylene penetrates, the experiment is stopped. The propylene capacity under the respective experimental conditions can be calculated from the time of first penetration (see Table 1).

The sample is subsequently flooded at room temperature with an increased amount of pure propane (about 100 standard liters / hr) for 30 minutes and the pressure setting for the next experiment is started again. The following repeated separations also provide the same values.

Example 2: Separation into an Al-terephthalic acid MOF-212 g of an Al-terephthalic acid MOF (3x3 mm and 1.5 χ 1.5mm pellets) are treated in a similar manner to Example 1.

Comparative Example 3: Molecular sieve separation 4302 g of 4Å molecular sieve (4-8 mesh) (1.5 mm extruded) are treated in a manner analogous to Example 1.

Comparative Example 4: Molecular Sieve Separation

13X molecular sieve (1.5mm extruded) is used in a manner analogous to Comparative Example 3.

<table> table see original document page 39 </column> </row> <table>

Example 5

An adsorber having a volume of about 0.21 is charged with, in each case, different adsorbents in the activated state and these are additionally released from residual moisture and adherent CO2 in a hot nitrogen stream prior to actual measurement. To determine the separation capacity, the adsorber is first flooded with pure compropane at room temperature and atmospheric pressure for 15 minutes and the system pressure is then increased to 5 bar. The pressure is regulated here through downstream needle valves. The feed is then switched to a propane / propene mixture (GC analysis: 54.7% propene, 44% depropane, equilibrium N2; flow: 16 1 standard / hr) and the concentration at the adsorbent outlet is monitored during time by means of an IR degas cell. Propylene capacity is calculated to the point of time at which a significant increase in propylene signal is first observed. The results are summarized in Table 2.

<table> table see original document page 40 </column> </row> <table>

Table 2

Figure 1 shows the IR signal for propylene versus time (penetration curves). Here the IR signal [a.u.] is plotted against time t (in min).

Individual curves refer to the adsorbents in Table 2 as indicated in Fig. 1.

Example 6:

In other experiments propylene was removed by adsorption of a gas mixture, which corresponds approximately to the propane dehydrogenation yield stream. Cu-BTC-MOF was used as a 1.5 mm extruded sorbent.

The gas mixture consisted of:

- ca. 1.5% ethane,

- ca. 1.5% ethylene,

- ca. 2% carbon monoxide

- ca. 2.5% methane

- ca. 30.8% propane

- ca. 30.8% propylene

- equilibrium hydrogen

The tests were performed on a tubular adiabatic reactor (2000 mm χ 35 mm Dl) equipped with a 10-fold thermal pair. The reactor feed was adjusted by the steel cylinders. The pressure was regulated by a valve in the leaked gas. Gas composition was determined by an inline FTIR analyzer at the reactor inlet and outlet.

Experimental Parameter:

Feeding: see Fig. 2 for experiment A and Fig. 3 for experiment B

Reactor pressure: 2.5 bar

Temperature: ambient temperature (ca. 20 0C)

Prior to testing the sorbent was purged overnight with hot dry nitrogen (ca. 50 ° C; 500 standard liters / hr) to remove residual traces of adsorbed water or CO2.

Experiment A:

In experiment A the reactor was pressurized with pure propane up to 2.5 bar. During propane adsorption a temperature rise of up to 50 K was observed. After the reactor cooled to room temperature, the feed gas mixture was allowed for adsorption.

Initially propylene and ethane were completely sorbed, as were the larger ethylene fractions and a small carbon dioxide fraction. Methane and propane passed unimpeded. After 10 min, the ethane concentration was increased in the naturally detached gas. After 56 min the ethylene concentration began to rise. Later or after 134 min, propene penetration occurred so that propene separation by desorption is possible.

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

In Fig. 2 propane and propylene concentrations as well as feed and pressure development are shown. Here the gas concentration (%) and the gas stream (1 standard / h) c and the pressure ρ (bar) are shown as a function of time (min). Curve 1 refers to the power supply current, curve 2 to the propane concentration, curve 3 to the pressure, and curve 4 to the propene concentration.

Experiment B:

In experiment Β, the reactor was pressurized with nitrogen to 2.5 bar. After pressurization, the feed mixture was admitted to the reactor.

Initially the entire gas mixture was adsorbed, resulting in a slight decrease in pressure within the reactor. Therefore, the flow was scaled up to 300 Nl / hr. After ca. After 25 min, methane and carbon monoxide penetration was observed at the reactor outlet, which reached its initial concentrations after 10 min. Little maistarde ethane, ethane and propane were almost coincidentally detected. Ethane and ethane reached initial concentrations after ca. 5 min Later, after 50 min, propene penetration occurred so that depropen separation by desorption is possible.

The pressure could not be kept absolutely constant during the whole experiment due to the large amount of adsorption. During the adsorption a temperature rise of 75 K was observed.

In Fig. 3, propane and propene concentrations, as well as feed and pressure development are shown. Here, gas concentration (%) and gas stream (1 standard / h) c and pressure ρ (bar) are shown as a function of time (min). Curve 1 refers to the power supply current, curve 2 to pressure, curve 3 to propane concentration, and curve 4 to propene concentration.

Claims (18)

A process for obtaining propylene from a gas stream comprising propylene and at least one other hydrocarbon, said process comprising the steps of (a) contacting the gas stream with an adsorbent comprising a porous metal organic structure comprising at least an at least bidentate organic compound, coordinated with at least one metal ion, resulting in the adsorbent becoming compropene charged, (b) propylene release from the compropene charged adsorbent. Process according to Claim 1, characterized in that the at least one other hydrocarbon is propane. Process according to Claim 1 or 2, characterized in that the gas stream comprises from 5 to 95% by volume of propene, based on the sum of the volume proportions of propene and the additional hydrocarbon or additional hydrocarbons of the degass stream. Process according to any one of claims 1 to 3, characterized in that the gas stream is an optionally purified product stream from propylene production. Process according to Claim 4, characterized in that the optionally purified product stream originates from a cracking process, propane dehydrogenation, olefin transformation or methanol / dimethyl ether conversion to propylene production or a mixture of streams. two or more of these propylene production processes. Process according to Claim 5, characterized in that the optionally purified product stream is derived from propane dehydrogenation to propene production. Process according to any one of claims 1 to 6, characterized in that the adsorbent is present in an adsorber. A process according to claim 7, characterized in that the adsorber is part of an adsorber system comprising at least three cooperating adsorber in displaced phases. Process according to claim 8, characterized in that propylene release is performed in a pseudo continuous mode of operation. Process according to any one of claims 1 to 9, characterized in that propylene release is carried out by changing at least one of the selected physical parameters from the group consisting of pressure and temperature. Process according to any one of Claims 1 to 10, characterized in that the released propylene has a purity above 95% by volume based on the sum of the volumes of additional propylene and hydrocarbon or additional hydrocarbons. Process according to any one of claims 1ali, characterized in that the contact is made in a temperature range of -50 to 250 ° C. Process according to any one of claims 1 to 12, characterized in that the contact is carried out at a pressure in the range of 1 to 40 bar (absolute). Process 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. Process according to any one of claims 1 to 14, characterized in that the at least one bidentate at least one organic compound is derived from a dicarboxylic, outetracarboxylic tricarboxylic acid or a sulfur analogue thereof. Process according to any one of claims 1 to 15, characterized in that the metallic organic structure is in the form of a shaped body. Process according to any one of claims 1 to 16, characterized in that the maximum pore diameter distribution is at least 0.4 nm. 18. Use of a porous metal organic structure comprising at least one at least bidentate organic compound, coordinated with at least one metal ion, said use characterized by the fact that it is for obtaining technical propylene from a gas stream comprising propylene and at least one other hydrocarbon. .