WO2007144324A1 - Process for preparing unsaturated hydrocarbons - Google Patents

Abstract

The present invention relates to a combined process for depleting or removing methane from a methane-containing gas mixture A and subsequent dehydrogenation, comprising the following steps 1) preparing a methane-enriched mixture B by contacting the methane-containing gas mixture A with at least one sorbent comprising a porous organometallic skeleton material, the skeleton material comprising at least one at least bidentate organic compound bound coordinatively to at least one metal ion; 2) preparing a methane-depleted gas mixture C by desorbing the compounds retained on the sorbent; 3) dehydrogenating aromatization of the saturated and unsaturated hydrocarbons present in mixture C or a portion thereof in the presence of a catalyst to aromatic hydrocarbons, to obtain a mixture D; 4) if appropriate separating the mixture D into a low boiler mixture E which comprises the majority of the H2 formed and of the unconverted hydrocarbons, and into at least one high boiler mixture F which comprises the majority of the aromatic hydrocarbons formed.

Description

Process for the preparation of unsaturated hydrocarbons

description

The present invention relates to a process for the preparation of unsaturated or aromatic hydrocarbons such as ethylene, benzene, toluene, ethylbenzene, styrene, xylene, naphthalene or mixtures thereof from gaseous raw materials such as natural gas.

Unsaturated or aromatic hydrocarbons, such as those mentioned above, are important intermediates in the chemical industry, whose demand is still increasing. As a rule, they are made from naphtha, which in turn is obtained from crude oil. Recent research shows that world oil reserves are limited compared to natural gas reserves. Therefore, it is desirable to produce aromatic hydrocarbons from educts that can be obtained from natural gas. The main component of natural gas is methane. The typical composition of natural gas is as follows: 50 to 99 mol% methane, 0.01 to 30 mol% ethane, 0.01 to 10 mol% propane, up to 4 mol% butane and higher Hydrocarbons, up to 3 mol% carbon dioxide, up to 0.30 mol% hydrogen sulfide, up to 12 mol% of nitrogen and up to 0, 5 mol% of helium and hydrogen.

The non-oxidative conversion of methane to benzene and hydrogen to form any by-products such as ethylene, naphthalene and other higher hydrocarbons has long been known (L. Wang, L. Tao, M. Xie, G. Xu, J. Huang, and Y Ku, "Dehydrogenation and aromatization of methane under non-oxidizing conditions", Catalysis Letters 21, 35-41 (1993)). This reaction is also referred to as dehydrating aromatization.

This reaction route represents an interesting opportunity to use natural gas as an alternative raw material for the production of benzene as a significant intermediate in the chemical industry. Sales of up to about 20% (S. Qi and B. Yang, "Methane aromatiziation using Mo-based catalysts prepared by microwave heating", Catalysis Today 98, 639-645 (2004)) and selectivities up to about 95% ( Qi et al.) Are described in the literature for the non-oxidative conversion of methane to benzene on a laboratory scale.

Thermodynamic considerations show in the dehydrating aromatization of

Methane limits the reaction by the position of the equilibrium (D. Wang,

JH Lunsford and MP Rosynek, "Characterization of a Mo / ZSM-5 catalyst for the conversion of methane to benzene", Journal of Catalysis 169, 347-358 (1997)). To Calculations taking into account the components methane, benzene, naphthalene and hydrogen is about the equilibrium conversion of the conversion of methane to benzene (and naphthalene) at 1 bar and 750 ° C at about 17%.

In order to make better use of the methane used, it is proposed, for example, in US 2003/0144565, to recycle the product stream from which the aromatic hydrocarbons formed were separated and thus to achieve a better yield of aromatics with respect to the methane used. However, the return reduces economic efficiency.

The exothermic conversion of methane to higher molecular weight compounds and aromatics under oxidative conditions, ie in the presence of an oxidizing agent, is also known. Both the use of oxygen / air (JB Claridge, M. Green, SC Tsang and APE York, "Oxidative Oligomerization of Methane to Aromatics", Applied Catalysis, A: General 89, 103-116 (1992); P. Tsai, "Oxidation of methane over H-ZSM5 and other catalysts", Applied Catalysis 19, 141-152 (1985)) as well as further oxidizing agent (Anderson et al.) Is described in the scientific literature. Claridge et al. describe selectivities of at best 29% for benzene and at the same time over 40% for CO and CO ₂ when reacting in a homogeneous gas phase. Heterogeneously catalyzed reactions provide selectivities for CO and CO ₂ of more than 50% on different catalysts in all cases. Benzene selectivities of a maximum of 20.8% are found here.

US 4,571,443 teaches the oxidative dehydrogenation of unsaturated substrates to the corresponding dimers. Certain H-substituted substrates can also cyclize as a side reaction and form aromatics.

Tan et al. show the conversion of methane to Mo-H-ZSM5 catalysts. In the presence of 1, 5 to 20% O ₂ , methane conversions of up to 17.4% are achieved with a benzene selectivity of 28.3%. The highest benzene selectivities are 55% (10.9% methane conversion).

US 4,822,944 discloses the oxidative pyrolysis of methane or natural gas at temperatures above 900 ° C on a mixed metal oxide. Turnover of up to 19% and yields of 0.2 to 2.8% are described here.

It turns out that, despite the use of the heat-providing reaction of the partial oxidation of the alkane, conversions of more than 20% or benzene yields of less than 10% based on the alkane are rarely achieved. The aromatization of C ₂ -C ₆ alkanes is extensively described in scientific publications and in the patent literature. In most cases an MFI-type zeolite (ZSM-5) with Ga or Zn is also used in combination with precious metals as a catalyst.

The location of the thermodynamic equilibrium is significantly more advantageous for the conversion of ethane, ethylene or propane in a dehydrogenating aromatization to benzene than for the direct conversion of methane to benzene. For example, the equilibrium in the conversion of ethane to benzene at 750 ° C and 1 bar is over 90% (calculated from the thermodynamic data).

In summary, the dehydrogenating aromatization of methane is thermodynamically less favorable than that of higher alkanes such as ethane or propane. Therefore, it would be beneficial to have a way to increase the yield and selectivity when using a methane-containing gas mixture in the dehydrogenating aromatization.

Furthermore, it can generally be said that the person skilled in the art is in the search for a process which enables a favorable utilization of natural gas (comprising a high proportion of methane besides ethane and possibly further constituents, mainly alkanes) to form unsaturated compounds.

The object of the present invention is to provide a method of dehydrating aromatization of methane-containing, a proportion of ethane and / or propane and / or butane-containing gas mixtures in which occurs mainly aromatization of ethane and / or propane. In particular, the object is to provide such a method, with which the methane present in the mixture is at least partially not utilized in the thermodynamically unfavorable hydroaromatization, but can be supplied to another utilization.

The object is achieved by a combined process of depletion or removal of methane from a methane-containing gas mixture A and subsequent reaction of the mixture A to unsaturated compounds comprising the following steps 1) preparing a methane-enriched mixture B by contacting the methane containing gas mixture A having at least one sorbent containing a porous organometallic framework material, wherein the framework material contains at least one coordinated to at least one metal ion, at least bidentate organic compound; 2) preparing a methane-depleted gas mixture C by desorbing the compounds trapped on the sorbent;

3) reacting the hydrocarbons contained in Mixture C or a part thereof to unsaturated hydrocarbons to obtain a mixture D;

4) optionally separating the mixture D.

In one embodiment of the present invention, the unsaturated hydrocarbon is benzene (variant I). In this case, the separation of the mixture D into a blending mixture E, which contains the main part of the resulting H ₂ and the unreacted hydrocarbons, and in at least one heavy remix F, which contains the majority of the unsaturated hydrocarbons formed takes place.

The benzene can also be cleaned overhead.

In a further embodiment of the present invention, the unsaturated hydrocarbon is ethylene (variant II). In this case, the separation of the mixture D into a C1 / C2 mixture and a mixture containing higher hydrocarbons by distillation and further separation of the C1 / C2 mixture in methane and ethane and optionally ethane and ethyne.

The ethylene is preferably dried and freed of CO ₂ , in particular by a so-called guard bed.

In a final embodiment of the present invention, the unsaturated hydrocarbon is ethylbenzene (variant IM). In this case, the separation of the mixture D into its main components is carried out by distillation. In general, the main constituents are benzene, ethylbenzene, diethylbenzene and polyethylbenzenes and residue. The separation preferably takes place in a distillation plant consisting of 4 columns.

The separation is known to the person skilled in the art. Reference is made here to Weisserel / Arpe, "Industrielle Organische Chemie, 5th edition, pages 370 and 371, the content of which is incorporated by reference in the present application.

Methane is an important source of energy and also serves as the starting material for a number of important syntheses. The most important natural source of methane is natural gas, where methane is the main component. Furthermore, methane can be produced by cracking or carbonization processes or from carbon monoxide or carbon dioxide and hydrogen. The multi-stage implementation of the reaction of methane-containing mixtures of unsaturated hydrocarbons as a product of value by combination with separation / depletion of methane allows a significantly increased overall balance of the process in terms of yield and energy input than in the direct one-stage implementation of methane-containing gases.

Due to the increased yield, the amount of optionally recycled starting materials is lower. The associated process steps such as separation operations, compression and heating are less expensive, if necessary, can be completely dispensed with.

The unsaturated hydrocarbons which can be obtained by the process according to the invention are known to the person skilled in the art. Preferred examples include ethylene, benzene, toluene, ethylbenzene, styrene, xylene, naphthalene, and mixtures thereof. As by-products and by-products are propylene and butene. These products of value can be obtained from the mixture C in various ways.

Examples of preferred processes for converting the components contained in mixture C into unsaturated hydrocarbons include the dehydrogenating aromatization (variant I), the dehydrogenation of ethane to ethylene (variant II), by cracking or dehydrogenation as such under various conditions can be carried out and the alkylation of aromatics to alkylaromatics, in particular from benzene to ethylbenzene (variant III).

In the present application, saturated hydrocarbons are branched and unbranched hydrocarbons having 1 to 6 C atoms, for example methane, ethane, propane, n-butane, i-butane, n-pentane and i-pentane. Unsaturated hydrocarbons are branched and unbranched hydrocarbons having at least 2 C atoms which have at least one double bond or triple bond, for example ethylene, acetylene, propene, propyne, 1-butene, 2-butene, isobutene, 1-butene. Butyne, 2-butyne, 1-pentene and 2-pentene.

The process according to the invention makes it possible in a simple manner to achieve a higher yield of unsaturated compounds, that is to say aromatics produced during the dehydroaromatization, than without a preceding separation step. The separation by sorption carried out in steps 1) and 2) thus brings about a high level of economic efficiency and a favorable economic balance of the process.

In the context of the present invention is spoken by "separating" and "tearing off" of methane. Both terms indicate the process that

Methane is removed from a methane-containing mixture, with only a portion of the Me- than (ie> 0 to <100% of the amount present) or all of the methane (100%) can be removed. Removing the total amount of methane (100%) is referred to as "complete" separation or "complete" removal.

The most common method of separating or depleting methane from methane-containing natural gas mixtures is the low-temperature pressure distillation. As a result, in particular the separation of methane and higher hydrocarbons, in particular ethane, propane and butane is possible. This separation is usually preceded by a desulfurization step and the removal of carbon dioxide. Likewise, the cryogenic pressure distillation is preceded by a drying step.

The separation of the carbon dioxide can also take place, for example, adsorptively with the aid of zeolites according to the prior art. Such a process is described, for example, in US Pat. No. 3,751,878. Alternatively, a so-called amine wash can be performed.

Adsorptive processes are often a cheaper alternative to the separation and purification of mixtures compared to distillation methods. This is especially true in the separation or purification of gases that must first be transferred to the liquid phase for distillative separation. A widely used adsorbent is activated carbon. However, this is problematic for safety reasons, because, for example, during its regeneration so-called smoldering can occur, which in turn constitute a fire hazard.

As mentioned above, zeolitic molecular sieves are alternatives to the activated carbon. However, their efficiency is limited in terms of uptake capacity and their separation efficiency. This applies in particular with regard to the enrichment of methane in methane-containing gas mixtures such as natural gas. Further disadvantages of zeolites are the high sorption energy as well as disadvantageous kinetics in the separation, which can be shown, for example, in the fact that it is necessary to work with high gas flows.

The individual process steps of the process according to the invention are set out below.

Step 1)

The Applicant has developed a method by which a separation / depletion of methane from methane-containing mixtures is possible in a simple manner, by sorption of the methane-containing mixtures of certain organometallic mate- rials, which will be described in more detail below. The method is the subject of the non-prepublished European patent application entitled "Adsorptive Enrichment of methane in methane-containing mixtures "with the registration number 05 027 616.1 from 16.12.2005 (Priority: DE 10 2004 061 238.2 from 20.12.2004).

The porous metal organic framework ("Metal-Organic-Framework (MOF)") allows more efficient depletion or removal of methane from methane-containing gas mixtures compared to molecular sieves, preferably by adsorptive removal of lower alkanes such as ethane, propane or butane and subsequent desorption takes place.

Preferably, the methane-containing gas mixture is natural gas or a mixture containing natural gas. Usually, the methane content in the methane-containing gas mixture before depletion is at least 50% by volume.

Preferably, the depletion of the methane is carried out by sorption and desorption of C ₂ -C ₄ alkanes from the methane-containing gas mixture. The sorption of the C ₂ -C ₄ alkanes by the sorbent can be selective for individual alkanes - that is ethane, propane, butane or isobutane - or mixtures of two or more of these alkanes can be separated. Particularly preferred is the sorption of ethane-containing alkanes or ethane.

The proportion of gases other than methane before depletion is preferably at most 50% by volume, more preferably at most 30% by volume, especially at most 20% by volume, and most preferably at most 10% by volume.

The proportion of C ₂ -C ₄ alkanes in the methane-containing gas mixture before depleting the methane is preferably at most 25% by volume, more preferably at most 20% by volume, in particular at most 15% by volume and most preferably at most 10 % By vol.

The amount of ethane in the methane-containing gas mixture before depleting the methane is preferably at most 25% by volume, more preferably at most 15% by volume, and most preferably at most 8% by volume.

The gas mixture can be brought into contact with the sorbent containing a porous organometallic framework material once or several times. Preferably, several cycles are performed. Here, after contacting the already enriched with methane methane-containing gas mixture is brought again in contact with the sorbent. As a result, increased depletion or even complete removal can be achieved. The gas mixture is preferably adsorbed continuously on one or more fixed beds, for example in a temperature or pressure swing adsorption with several parallel beds. In this case, the gas mixture is passed through the sorption bed or sorption beds. Further preferably, the continuous adsorption takes place in one or more shaft or tubular reactors, in particular in one or two shaft reactors, wherein at least one reactor is filled with an adsorbent containing a porous organometallic framework. There are also reactor cascades conceivable. A reactor may contain a partial filling with a porous organometallic framework or a combination bed, for example with additional other adsorbents.

The adsorption is carried out at a pressure ranging from 1 bar (atmospheric pressure) to 325 bar. Particularly preferably, the pressure is in a range from 1 bar to 250 bar, in particular between 1 and 100 bar and most preferably between 3 and 80 bar.

The temperature of the gas mixture upon contact with the sorbent containing a porous organometallic framework is preferably about 5 ° C. However, both higher and lower temperatures can be used. Thus, temperatures from a range of -100 ° C to + 450 ° C are conceivable. A typical temperature is in the range of -20 ° C to + 30 ° C, preferably from 0 ° C to 10 ⁰ C.

The gas mixture is preferably brought into contact with the sorbent at a volume-related flow rate per adsorbent volume (GHSV = gas hourly space velocity) of 250 l / h to 10,000 l / h, particularly preferably from 250 l / h to 2,500 l / h.

The mixture A contains at least 50 mol%, preferably at least 60 mol%, particularly preferably at least 70 mol%, very preferably at least 80 mol%, in particular at least 90 mol% methane

In general, the mixture A in addition to methane usually contains 0.01 to 15 mol%, ethane, usually 0.01 to 10 mol% propane and optionally butane and higher hydrocarbons in proportions, which are usually up to 4 ιmol-% lie.

Furthermore, the mixture A may usually contain up to 12 mol .-% of nitrogen.

The mixture A may additionally contain gases from the group comprising hydrogen, water vapor, carbon monoxide, carbon dioxide, nitrogen and noble gases. The methane contained in Mixture A may be derived from natural gas or petroleum refining, synthetically produced, for example, by the Fischer-Tropsch synthesis, or recovered from regenerative sources.

In one embodiment, commercially available natural gas may be used as mixture A, optionally after purification known to a person skilled in the art.

In a further embodiment, methane-containing gas obtained directly during petroleum refining can also be used, possibly after a purification known to a person skilled in the art.

The preferred source is so-called H-gas, ie a natural gas with a high C ₂ content.

The mixture B obtained after sorption of the hydrocarbons having at least 2 carbon atoms contains the components present in mixture A in modified proportions, in particular the content of methane is higher. The mixture B can be used, for example, as follows:

(a) combustion in thermal power stations (under energy, heat and / or steam), in particular in gas and steam power plants (GUD); b) the synthesis of synthesis gas by steam reforming or partial oxidation; c) the reaction with ammonia to hydrocyanic acid in the presence of oxygen by the Andrussow process, or without addition of oxygen according to the BMA process (hydrocyanic acid from methane and ammonia); d) the reaction with sulfur to carbon disulfide; e) the pyrolysis to acetylene in the light floor or by the Sachsse Bartholome- method; f) the oxidative coupling to ethylene.

Step 2)

The mixture C obtained after desorption in step 2) contains the components contained in mixture A in modified proportions. The desorption of the separated gas and gas mixture located on the adsorbent can be carried out by means of nitrogen purge gas under conditions in which the separation (enrichment) is also carried out. Other options for desorption exist by means of pressure or temperature change. Preferably, the desorption takes place under pressure change. The manner in which desorption can be carried out is known to the person skilled in the art. Instructions on this can be found for example in Werner Käst, "Adsorption from the gas phase", Verlag VCH, Weinheim, 1988. After desorption, further streams can be added to the stream to be processed. -

Step 3) Step 3), ie the conversion of the hydrocarbons contained in the mixture C to unsaturated compounds, can be carried out in various ways. According to the present invention, in a first embodiment this is the dehydrating aromatization (variant I). In a further embodiment this is the dehydrogenation of the ethane contained in C) to ethylene (variant II). In a third embodiment, this is the alkylation of the aromatic formed in the first embodiment with the unsaturated compounds formed in the further embodiment, preferably the production of ethylbenzene by alkylation of benzene with ethylene (variant IM). The formation of aromatics and the formation of ethylene are carried out independently. In a variant of the third embodiment, the ethylbenzene can be dehydrogenated to styrene.

For the purposes of the present invention, "unsaturated compound" means an olefin, an alkyne or an aromatic compound.

Variant I (aromatization)

In one embodiment of the dehydrogenating aromatization carried out in step 3) is the reaction of saturated or unsaturated hydrocarbons to aromatics with H ₂ cleavage. The dehydrating aromatization is an endothermic reaction, so heat must be supplied to maintain the desired reaction temperature.

To this end, the mixture C is introduced in step 3) into a reaction zone in which the hydrocarbons containing at least 2 C atoms or a part thereof in the presence of a catalyst are reacted in a dehydrogenating aromatization to give aromatic hydrocarbons. Depending on the reaction conditions and catalysts used, methane can be converted into aromatics in addition to the abovementioned saturated and unsaturated hydrocarbons having at least 2 carbon atoms.

Usually, the mixture C) contains mostly ethane, besides mainly alkanes such as propane and butane. Not separated methane can z.T. be present in significant concentrations.

The dehydrogenating aromatization of the saturated and unsaturated hydrocarbons present in mixture C is known per se. It can be under feed or without Supply of oxygen-containing gases to known catalysts under conditions known to those skilled in the art.

Particularly suitable catalysts for carrying out the dehydrogenating aromatization without supply of oxygen-containing gases are aluminosilicates of the pentasil type, in particular ZSM zeolites such as ZSM-5, ZSM-8, ZSM-11, ZSM-23 and ZSM-35, preferably ZSM-5 or MCM zeolites such as MCM-22.

The zeolites may contain, in addition to AI, other elements of the 3rd main group, such as Ga, B or In. In such a case, Ga-containing zeolites are preferred, which may be present as framework or extra-frame work. Suitable counterions for the produced by the trivalent framework cations excess negative charge can be H ^+, Na ^+, Li ^+, K ^+, Rb ^+, Cs ^+, NH ₄ ^+, Mg ^2+, Ca ^2+, Sr ²⁺ and Ba ⁺ in Be included zeolite.

The zeolites may contain, in addition to Si, further elements of the 4th main or subgroup, such as Ti, Ge or Sn.

The zeolites may be doped with one or more other metals from the group of transition metals. Of these, preference is given to using Mn, Mo, Pd, Pt, Ru, Cu, Co, Fe, Re, W or Zn; particular preference is given to using zeolites doped with Ga, Zn, In, Mo, W or Pt.

It is also possible to add to the catalyst one or more further metals or compounds thereof, for example Cu, Co, Fe, Pt or Ru, preference is given to Cu.

For example, Cu-promoted Mo / ZSM-5 zeolite catalysts have been described in the literature (Qi et al., Catalysis Today 98, 639 (2004)) or Ga / ZSM-5 zeolite catalysts promoted with a Group VIIIB metal of the periodic table ( US 4,727,206). Particular molybdenum-modified ZSM-5 zeolites are described in WO 02/10099.

In / HZSM-5, Ga / HZSM-5, Zn / HZSM-5, Re / HZSM-5 can also be used, as well as W / HZSM-5, promoted with Mn, Zn, Ga, Mo or Co.

It is also preferred to use MCM-22 supported catalysts which may be promoted with Zn, Ga, In, Mo, W and / or Pt. However, Re / HMCM-22 can also be used.

Usually, the dehydrogenating aromatization of hydrocarbons, which is operated without supply of oxygen-containing gas streams, at the above-mentioned catalysts at temperatures of 400 to 1000 ° C, preferably from 450 to 900 ° C, particularly preferably from 500 to 800 ° C, in particular from 550 to 750 ° C, at a pressure of 0.5 to 100 bar, preferably at 1 to 50 bar, more preferably at 1 to 30 bar, in particular 1 to 10 bar , carried out. Usually, the reaction is carried out at a GHSV (gas hourly space velocity) of 100 to 10,000 h ^-1 , preferably 200 to 3000 h ^-1 .

It may be advantageous to activate the catalyst used in the dehydrogenating aromatization of hydrocarbons without the supply of oxygen-containing gas streams, especially in the case of the metals Mo, W, Re, before the actual use.

This activation can be carried out with methane-containing gas stream or a C ₂ -C ₄ alkane, for example ethane, propane, butane or a mixture of these, preferably butane is used. The activation is carried out at a temperature of 350 to 650 ° C, preferably at 400 to 550 ° C, and a pressure of 0.5 to 5 bar, preferably at 0.5 to 2 bar performed. Usually, the GHSV (gas hourly space velocity) at activation is 100 to 4000 h ^-1 , preferably 500 to 2000 h ^-1 .

It is also possible to carry out an activation by the hydrocarbons having at least 2 carbon atoms contained in mixture C. The activation is carried out at a temperature of 250 to 650 ° C, preferably at 350 to 550 ° C, and a pressure of 0.5 to 5 bar, preferably at 0.5 to 2 bar performed. Usually, the GHSV (gas hourly space velocity) at activation is 100 to 4000 h ^-1 , preferably 500 to 2000 h ^-1 . In a further embodiment, it is also possible to additionally add hydrogen.

Of course, the catalyst used in decreasing activity can be regenerated by conventional methods known in the art, especially if the step 3) is carried out without the addition of oxygen-containing gas streams. In particular, treatment with an oxygen-containing mixture, such as air, enriched air or pure oxygen, in which the oxygen-containing mixture is passed over the catalyst instead of the mixture C, should be mentioned here. However, it is also possible, for example, to regenerate the catalyst with hydrogen. This can be done by adding a hydrogen stream to the mixture C, for example. The ratio of hydrogen stream to mixture C is usually in the range of 1: 1000 to 2: 1, preferably 1: 500 to 1: 5.

The dehydrogenating aromatization in step 3) can in principle be carried out in all reactor types known from the prior art. A comparatively detailed description of inventively suitable reactor types contains also "Catalytica® Studies Division, Oxidative Dehydrogenation and Alternative Deoxidation Processes" (Study Number 4192 OD, 1993, 430 Ferguson Drive, Mountain View, California, 94043-5272, USA).

Suitable reactor forms are the fixed bed tube and tube bundle reactors. In this case, the catalyst is as 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 dehydrogenating aromatization tube bundle reactor comprises about 300 to 1000 reaction tubes. The catalyst geometry can be, for example, spherical or cylindrical (hollow or full), ring-shaped, saddle-shaped or tablet-shaped. Furthermore, extrudates, e.g. in strand, trilobe, quadrulobe, star or hollow cylinder form in question.

The dehydrogenating aromatization in step 3) can also be carried out in heterogeneously catalyzed manner in the fluidized bed. In a particular embodiment, the reactor contains a fluidized bed, but it may also be appropriate to operate a plurality of fluidized beds side by side, one or more of which are usually in the state of regeneration or reactivation.

The dehydrating aromatization can also be 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 Horde 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 reactor with only one horde. The dehydrogenating aromatization in step 3) is preferably carried out in a tube bundle or fluidized bed reactor.

The product of the dehydrating aromatization is a mixture D obtained, this preferably contains one or more aromatic hydrocarbons from the group benzene, toluene, ethylbenzene, styrene, xylene and naphthalene. In particular, the mixture contains D as aromatic hydrocarbons benzene and naphthalene, most preferably benzene.

Variant II (production of ethylene)

In a further embodiment of the present invention, the ethane contained in the mixture C is dehydrogenated to ethylene. This dehydrogenation reaction is known per se to a person skilled in the art and can be carried out in various ways.

In one embodiment, the dehydrogenation occurs in a cracking reaction. In this case, the optionally present, higher alkanes such as propane or butane are converted into ethylene.

The cracking is preferably carried out thermally, that is to say under non-catalytic conditions. The procedures followed are steam cracking and catalytic cracking ("cat cracking"), which are known to the person skilled in the art Depending on the composition of the starting material and the desired product spectrum, one of the two mentioned process variants can be used.

The preferred steam cracking process is usually carried out at conditions of 800 to 850 ° C, other variants may require depending on the desired product range, other temperatures between 600 and 1100 ° C.

Depending on the desired product spectrum and the composition of the starting products, the person skilled in the art will adjust the reaction conditions accordingly.

An overview of the common cracking reactions can be found in Weissermel, Arpe, "Industrial Organic Chemistry", 5th edition 1998, pages 65 to 99. The content of the passages mentioned is an important part of the present invention. In particular, the disclosure on pages 65-74, end of the first paragraph, is incorporated by reference into the present application.

The ethylene can also be obtained by dehydrogenation of ethane. Corresponding methods are known to the person skilled in the art.

In one embodiment, the dehydrogenation may be effected oxidatively in the presence of oxygen, for example molecular oxygen. Suitable catalysts are compounds based on alkali metals and alkaline earth metals, based on transition metal oxides and rare earth metal oxides.

The dehydration can also be done without the addition of oxygen. In this case, chromium oxides such as zeolite-based catalysts, for example, mordenite or mordenite with Ga, Zn, Pt or Ru, are used.

Variant IM (Preparation of Ethylbenzene) In a third embodiment of the process according to the invention, ethylbenzene is prepared. This is done by reacting ethylene with benzene. It is possible lent that only one of the two components (ie either benzene or ethylene) produced in step 3) of the method according to the invention and the other component is purchased. In one embodiment of the process according to the invention, both starting materials are obtained by the process according to the invention.

In any case, ethylene and benzene are each cooled in a separate process step. In the ethylene production / benzene production step 3) according to the invention following step 3i), the ethylene and / or benzene obtained in step 3) is then converted in a manner known per se to benzene.

The alkylation of benzene to ethylbenzene is known in principle. It can be in the liquid phase (with Friedel-Crafts catalysts, for example AICI3, BF ₃ , FeCl ₃ , ZnCl ₄ , SnCl ₄ or H ₃ PO ₄ ) or in the gas phase (with different supported catalysts, Al silicates, zeolites or supported Friedel -Crafts catalysts).

For a review of the alkylation of benzene with ethylene, see Weissermel, Arpe, "Industrielle Organische Chemie," 5th Edition, 1998, pages 369-373. The disclosure on the aforementioned pages is an integral part of the present application and incorporated by reference.

In another embodiment, the resulting ethylbenzene can be dehydrogenated to styrene.

Furthermore, in all embodiments, the mixture contains D in addition to unreacted methane and originally present in the mixture A and in step 3) hydrocarbons already contained in the mixture A inert gases such as nitrogen or helium and other noble gases and already in the mixture A contained impurities in changed shares. Furthermore, by-products such as CO, CO ₂ , H ₂ O or H ₂ and residues of unconsumed oxidizing agent formed in the mixture D in the reactions in steps 2) and 3) may be present.

Step 4)

Variant I

The separation of the mixture D in the case of the production of aromatics by dehydroaromatization into the low-mix mixture E and the high-boiling mixture F in step 4) takes place by condensation or else fractional condensation. By fractionated condensation is meant here a multi-stage distillation in the presence of larger quantities of inert gas. Thus, the mixture D can be cooled to -30 ° C to 80 ° C, preferably to 0 ° C to 70 ° C, more preferably to 30 ° C to 60 ° C. This condenses the aromatic hydrocarbons and high boilers while the unreacted methane and the hydrogen formed are present in gaseous form and thus can be separated by conventional methods. Optionally, the blending mixture E also contains the abovementioned inert gases and hydrocarbons, as well as the by-products formed and / or impurities already present in mixture A, and optionally unreacted oxidizing agent.

In a particular embodiment, it may be advantageous to free the mixture D in several stages of high boilers. For this purpose, this is for example cooled to -30 ° C to 80 ° C, the high-boiling mixture F ', which contains a portion of the high boilers, separated and the Leichtsiedenemisch E' compacted and further cooled, so that the high-boiling mixture F and the low-mix E. A compression is preferably carried out to a pressure level of 5 to 100 bar, preferably 10 to 75 bar and more preferably 15 to 50 bar. In order to achieve a substantial condensation of a particular compound, a correspondingly appropriate temperature is set. If the condensation is below 0 ° C, a previous drying of the gas may be necessary.

The high-boiling mixture F contains primarily the aromatic hydrocarbons such as benzene and naphthalene, the low-boiler mixture E contains the unreacted methane and the unreacted in step II saturated and unsaturated hydrocarbons and the volatile by-products formed and optionally the above-mentioned inert gases and / or already in Mixture A contained impurities. Among the readily volatile by-products are, for example, CO, CO ₂ and H ₂ . The unreacted hydrocarbons, preferably the 1 to 4 C-containing hydrocarbons, more preferably methane, and the hydrogen formed may optionally be separated by conventional methods.

The aromatic hydrocarbons contained in the high-boiling mixture F can be separated and / or purified by customary methods.

In one embodiment of the present invention, one or more components of the blending mixture E may be partially or completely separated.

The separation of the non-condensable or low-boiling constituents such as hydrogen, oxygen, carbon monoxide, carbon dioxide and nitrogen present in the low-boiling mixture E can be carried out in an absorption / desorption cycle with the aid of a high-boiling absorbent to obtain a mixture containing the absorbent and the saturated and unsaturated, preferably having 1 to 4 carbon atoms containing hydrocarbons, and a mixture containing the remaining, non-condensable or low-boiling constituents from the low-mix E. Inert adsorbents used in the absorption stage are generally high-boiling, non-polar solvents in which the dC ₄ -hydrocarbon mixture to be separated has a significantly higher solubility than the other gas constituents to be separated off. The absorption can be carried out by simply passing the low-boiling mixture E through the absorbent. But it can also be done in columns. It can be used in cocurrent, countercurrent or cross flow. Suitable absorption columns include plate columns having bubble-cap, valve, and / or sieve trays, columns with structured packings, for example fabric packings or sheet-metal packings with a specific surface area of 100 to 1000 m ² / m ³ as Mellapak ^® 250 Y, and packed columns, for example with balls , Rings or saddles made of metal, plastic or ceramic as packing. However, there are also trickle and spray towers, graphite block absorbers, surface absorbers such as thick-film and thin-layer absorbers and rotary columns, dishwashers, cross-flow scrubbers, rotary scrubbers and bubble columns with and without internals into consideration.

Suitable absorbents are comparatively non-polar organic solvents, for example C ₅ -C ₈ -alkenes, naphtha or aromatic hydrocarbons, such as the paraffin distillation medium fractions, or bulky group ethers, or mixtures of these solvents, which contain a polar solvent such as 1, 2-Dimethyl phthalate may be added. Suitable absorbents are also esters of benzoic acid and phthalic acid with straight-chain C 1 -C ₈ -alkanols, such as n-butyl benzoate, methyl benzoate, ethyl benzoate, dimethyl phthalate, diethyl phthalate, and so-called heat transfer oils, such as biphenyl and diphenyl ether, their chlorinated derivatives and triaryl alkenes. A geeigne- tes absorbent is a mixture of biphenyl and diphenyl ether, preferably in the azeotropic composition, for example, the commercially available Diphyl ^®. Frequently, this solvent mixture contains dimethyl phthalate in an amount of 0.1 to 25 wt .-%. Suitable absorbents are furthermore pentanes, hexanes, heptanes, octanes, nonanes, decanes, undecanes, dodecanes, tridecanes, tetradecanes, pentadecanes, hexadecanes, heptadecans and octadecanes or fractions obtained from refinery streams which contain as main components said linear alkanes.

Carbon dioxide can be removed, for example, with a selective absorption medium from the low-boiling mixture E or from the hydrocarbon obtained after separation of the 1 to 4 C atoms. Again, in the absorption stage, absorbents can be used, such as basic detergents known to the person skilled in the art, in which the carbon dioxide to be separated off has a significantly higher solubility than the other gas constituents to be separated off. The absorption can be achieved by simply passing the blending mixture E or the mixture obtained after separation of the saturated and unsaturated hydrocarbons from the blending mixture E by the absorbent. It can also be done in columns. It can be used in cocurrent, countercurrent or cross flow. Technically come here the device solutions listed above into consideration.

To separate off the hydrogen, the low-boiling mixture E or the mixture obtained after the removal of the saturated and unsaturated hydrocarbons from the low-boiling mixture E, optionally after cooling, for example in an indirect heat exchanger, can be passed through a membrane which is usually designed as a tube and which is only suitable for molecular hydrogen is permeable.

Alternatively, individual components can also be separated by chemical reaction. For example, the resulting hydrogen can be removed after oxidation as water from the mixture by condensation.

Alternatively, components can be separated in an adsorption process (thermal or pressure swing adsorption). In this case, an adsorbent cyclically charged in a first phase with the hydrogen-containing stream, all components except hydrogen, as well as the hydrocarbons are retained with one to four carbon atoms by adsorption. In a second phase, these components are desorbed again by reduced pressure or elevated temperature.

The molecular hydrogen separated in this manner can, if necessary, be used at least partially in a hydrogenation or else be supplied to another utilization, for example for the generation of electrical energy in fuel cells.

Alternatively, with sufficiently different boiling points, the rectification can also be used to separate off individual components.

A separation of individual components is generally not completely complete, so that in the hydrocarbons having 1 to 4 carbon atoms - depending on the nature of the separation - still small amounts or even traces of other gas components may be present.

In a further embodiment, a return of a portion of the low-mix mixtures E and E 'can be carried out. These low-boiler mixtures E and E 'are obtained by partially or completely separating the heavy or aromatic hydrocarbons from the mixture D. A portion of the mixtures E and / or E 'are optionally recycled by the direct metering into the reaction zone 1 or 2 or by the previous combination with the mixture A or the mixture C. The proportion of recycled electricity is between 1 and 95% of the corresponding mixture E or E ', preferably between 5 and 90% of the corresponding mixture E or E'.

Optionally, the recirculated streams may be completely or partially freed of the above-listed methods of hydrogen and optionally other low-boiling components which are not hydrocarbons.

In a further embodiment of the present invention, hydrocarbons having 2 to 4 C atoms can be selectively separated from the low boiler mixture E, before or after separation of the low-boiling components such as CO, CO ₂ or hydrogen, and recycled to the second reaction zone.

The recirculation of a stream may e.g. with the aid of a compressor, a blower or a nozzle. In a preferred embodiment, the nozzle is a propulsion jet nozzle, wherein the mixture A, mixture C or an oxygen-containing stream or a vapor stream is used as a propellant.

According to a further embodiment of the present invention, the unreacted hydrocarbons contained in the low-boiler mixture E and the hydrogen formed can be fed to a further hydrocarbon-consuming process. Examples of methane consuming processes are

a) Combustion in thermal power plants (under energy, heat and / or steam extraction), in particular in gas and steam power plants (GUD); b) the synthesis of synthesis gas by steam reforming or partial oxidation; c) the reaction with ammonia to hydrocyanic acid in the presence of oxygen by the Andrussow process, or without addition of oxygen according to the BMA process (hydrocyanic acid from methane and ammonia); d) the reaction with sulfur to carbon disulfide; e) the pyrolysis to acetylene in the light floor or by the Sachsse Bartholome- method; f) the oxidative coupling to ethylene.

As hydrocarbon-consuming processes are a) and b) called.

It may be advantageous to partially or completely separate the hydrogen formed prior to use in the methane consuming process, such as processes b) to f). For this purpose, the methods mentioned above, the methods listed above can be used and the hydrogen thus obtained in turn for energy production or in a hydrogen-consuming process, such as a hydrogenation, are used. If appropriate, it may also be advantageous to separate the above-mentioned inert gases, the unreacted saturated and unsaturated hydrocarbons and the by-products formed by conventional processes before use in the methane or hydrocarbon-consuming process.

Preferably, the low-boiler mixture E is fed to the combustion in thermal power plants for energy, heat and / or steam extraction.

The dehydrogenating aromatization is associated with the formation of hydrogen, whereby the calorific value of the low-mix mixture E changes.

Variant II

In the case of ethylene production, the separation is generally by distillation.

Corresponding methods are known to the person skilled in the art.

In a further embodiment of the present invention, the separation of the mixture D by distillation into a C1 / C2 mixture E and a mixture F 'containing higher hydrocarbons and further separation of the C1 / C2 mixture in methane and ethylene and optionally ethane and ethyne.

The ethylene is preferably dried and freed of CO ₂ , in particular by a so-called guard bed.

Variant IM In the case of the production of ethylbenzene, the separation of the ethylbenzene from the remaining constituents of the mixture D takes place by distillation. Corresponding methods are known to the person skilled in the art.

The exact workup depends on which compounds are present in the educt streams containing benzene and ethylene and which are obtained in variant II or IM or in both variants.

MOF materials

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, M. O-Keeffe et al., J. Sol. State Chem., 152 (2000), pages 3 to 20, H. Li et al., Nature of Unit 2, (1999), page 276, M. Eddaoudi et al., Topics in Catalysis θ, (1999), p 105 to 1111, B. Chen et al., Science 291_, (2001), pages 1021 to 1023 and DE-A-101 1 1 230. The MOFs 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. 45, page 71, in particular on page 79 (FIG. 1976). 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 (DIN 66131, 66134) for a MOF 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 and particularly preferably more than 1000 m ² / g.

The metal component in the framework of the present invention is preferably selected from Groups Ia, IIa, MIa, IVa to Villa and Ib to VIb. 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. More preferred are Zn, Cu, Ni, Pd, Pt, Ru, Rh and Co. With respect to the ions of these elements, mention is particularly 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 ) ₂ -C (RNH ₂ ) ₃ , -CH (ROH) ₂ , -C (ROH) ₃ , -CH (RCN) ₂ , -C (RCN) ₃ wherein R For example, preference is given to an alkylene group having 1, 2, 3, 4 or 5 carbon atoms, for example 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 C ₆ rings, which may optionally be condensed and may be independently substituted with at least one substituent each suitably, and / or each independently at least one heteroatom such as N, O and / or S can contain NEN. 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 containing these functional groups is capable of forming the coordinate bond and for preparing the framework material.

Preferably, the organic compounds containing the at least two functional groups are derived from a saturated or unsaturated aliphatic compound or an aromatic compound or an aliphatic as well as an 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 1 1 and especially 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 from each other can continue each nucleus of said compound contains at least one heteroatom such as 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.

For example, 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, are examples of the present invention. 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- Benzenedicarboxylic acid, p-benzenedicarboxylic acid, imidazole-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, diimidedicarboxylic 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, Pe ethylene di-3,9-dicarboxylic acid, perylenedicarboxylic acid, Pluriol E 200-dicarboxylic acid, 3,6-dioxaoctanedicarboxylic acid, 3,5-cyclohexadiene-1-dicarboxylic acid, octadicarboxylic 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-2,2'-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) -phenylpyrazoline-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 acid, 2,2'-biquinoline-4,4'-dicarboxylic acid, pyridine-3,4-dicarboxylic acid, 3,6,9-trioxaundecane-dicarboxylic acid, O-hydroxy-benzophenone-dicarboxylic acid, Pluriol E 300- dicarboxylic acid, Pluriol E 400 dicarboxylic acid, Pluriol E 600 dicarboxylic acid, pyrazole-3,4-dicarboxylic acid, 2,3-pyrazinedicarboxylic acid, 5,6-dimethyl-2,3-pyrazine dicarboxylic acid, 4,4 ' Diaminodiphenyl ether di-imiddicarboxylic acid, 4,4'-diaminodiphenylmethanedimide dicarboxylic acid, 4,4'-diaminodiphenylsulfonediimide dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,3-adamantanedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3- Naphthalenedicarboxylic 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 ^l , 3'-diphenyl-p terphenyl-4,4'-dicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, imidazole-4,5-dicarboxylic acid, 4 (1H) -oxo-thiochromene-2,8-dicarboxylic acid, 5-tert-butyl- 1, 3-benzenedicarboxylic acid, 7,8-quinolinedicarboxylic acid, 4,5-imidazoledicarboxylic acid, 4-cyclohexene-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, 1-nonene-6,9-dicarboxylic acid, eicosene-dicarboxylic 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, α, ω-dicarboxylic acid, α, ω-di-chlorofluorubin, ω-dicarboxylic acid, 7 Chloro-3-methyl-quinoline-6,8-dicarboxylic acid, 2,4-dichlorobenzophenone-2 ', 5'-dicarbo acid, 1, 3-benzenedicarboxylic acid, 2,6-pyridinedicarboxylic acid, 1-methylpyrrole-3,4-dicarboxylic acid, 1-benzyl-1-H-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-tetra-decanedicarboxylic 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- Benzene tricarboxylic acid, 1, 2,4-butane tricarboxylic acid, 2-phosphono-1, 2,4-butanetricarboxylic acid, 1, 3,5-benzenetricarboxylic acid, 1-hydroxy-1,2,3-propanetricarboxylic acid, 4,5-diol hydro-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-tricarboxylic acid, 1, 2,3-propane tricarboxylic acid or auric tricarboxylic acid, or tetracarboxylic acids such as

1, 1-dioxide-peroxy [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-sulfonic acid 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-hexane tetracarboxylic acid, 1, 2,7,8-octanetetracarboxylic acid, 1, 4,5,8-naphthalene tetracarboxylic acid, 1,2,9,10-decantetracarboxylic acid, benzophenone tetracarboxylic acid, 3,3 ', 4,4'-benzoic acid. phenontetracarboxylic acid, tetrahydrofurantetracarboxylic acid or 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, monocarboxylic dicarboxylic acids, monocernic tricarboxylic acids are preferred. acids, monocarboxylic tetracarboxylic acids, dicerate dicarboxylic acids, dicerated tricarboxylic acids, dicerous tetracarboxylic acids, tricarboxylic dicarboxylic acids, tricarboxylic tricarboxylic acids, tricyclic 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 0. A suitable substituent in this regard is, inter alia, -OH, a nitro group, an amino group or an alkyl to name or alkoxy.

Particular preference is given as at least bidentate organic compounds to acetylenedicarboxylic acid (ADC), benzenedicarboxylic acids, naphthalenedicarboxylic acids, biphenyldicarboxylic acids such as, for example, 4,4'-biphenyldicarboxylic acid (BPDC), biphenyldicarboxylic acids such as, for example, 2,2'-bipyridine dicarboxylic acids such as 2,2'-biphenyl dicarboxylic acids. 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, Naphthalenedicarboxylic acid, 1, 5-naphthalenedicarboxylic acid or 2,6-naphthalenedicarboxylic acid 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, caustic soda, 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 further preferred if more than 25% of the total pore volume, in particular more than 50% of the total pore volume, is formed by pores 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 ranging in diameter or up to 10 nm. The pore distribution can be determined by means of mercury porosimetry.

The following are examples of MOFs. In addition to the identification of the MOF, the metal and the at least bidentate ligands, the solvent and the cell parameters (angles α, β and γ and the distances A, B and C in A) are also given. The latter were determined by X-ray diffraction.

ADC acetylenedicarboxylic acid NDC naphthalene dicarboxylic acid BDC benzene dicarboxylic acid ATC adamantanetetracarboxylic acid BTC benzene tricarboxylic acid BTB benzene tribenzoic acid MTB methane tetrabenzoic acid ATB adamantane tetrabenzoic acid ADB adamantane dibenzoic acid

Other MOFs are MOF-177 and MOF-178, which are described in the literature.

In addition to the conventional method for producing the MOF, as described for example in US 5,648,508, they can also be prepared by electrochemical means. In this regard, reference is made to DE-A 103 55 087 and WO-A 2005/049892. The MOFs produced in this way especially good properties in connection with the adsorption and desorption of chemical substances, in particular of gases. They thus differ from those produced conventionally, even if they are formed from the same organic and metal ion constituents, and are therefore to be regarded as new framework materials. In the context of the present invention, electrochemically produced MOFs are particularly preferred.

Accordingly, the electrochemical preparation relates to a crystalline porous organometallic framework comprising at least one coordinated to at least one metal ion at least bidentate organic compound which in a reaction medium containing the at least one bidentate organic compound at least one metal ion by oxidation of at least one anode containing the corresponding metal is produced.

The term "electrochemical preparation" refers to a production process in which the formation of at least one reaction product is associated with the migration of electrical charges or the occurrence of electrical potentials.

The term "at least one metal ion" as used in the context of electrochemical fabrication refers to embodiments according to which at least one ion of a metal or at least one ion of a first metal and at least one ion of at least one second metal different from the first metal be provided by anodic oxidation.

Accordingly, the electrochemical preparation comprises embodiments in which at least one ion of at least one metal is provided by anodic oxidation and at least one ion of at least one metal via a metal salt, wherein the at least one metal in the metal salt and the at least one metal, via anodic oxidation as Metal ion, may be the same or different. Thus, for example, with respect to electrochemically produced MOF, the present invention encompasses an embodiment in which the reaction medium contains one or more different salts of a metal and the metal ion contained in that salt or salts is additionally provided by anodic oxidation of at least one anode containing that metal , Likewise, the reaction medium may contain one or more different salts of at least one metal and at least one metal other than these metals may be provided via anodic oxidation as the metal ion in the reaction medium.

According to a preferred embodiment of the present invention, the at least one metal ion is oxidized by anodic oxidation of at least one of the minium ions. at least one metal-containing anode is provided, wherein no further metal is provided via a metal salt.

The term "metal" as used in the context of the present invention in connection with the electrochemical preparation of MOFs includes all elements of the periodic table which can be provided via anodic oxidation by electrochemical means in a reaction medium and with at least one at least bidentate organic compounds at least one organometallic porous framework material are capable of forming.

Regardless of its preparation, the obtained MOF is obtained in powdery or crystalline form. This can be used as such as a sorbent in the process according to the invention alone or together with other sorbents or other materials. This is preferably done as bulk material, in particular in a fixed bed. Furthermore, the MOF can be converted into a shaped body. Preferred methods here are the extrusion or tableting. In molded article production, additional materials such as binders, lubricants, or other additives may be added to the MOF. Likewise, it is conceivable that mixtures of MOF and other adsorbents, for example activated carbon, are produced as shaped articles or separately give shaped articles, which are then used as shaped-body mixtures.

With regard to the possible geometries of these MOF shaped bodies, there are essentially no restrictions. For example, pellets such as disk-shaped pellets, pills, spheres, granules, extrudates such as strands, honeycombs, lattices or hollow bodies may be mentioned.

In principle, all suitable processes are possible for producing these shaped bodies. In particular, the following procedures are preferred:

Kneading the framework material alone or together with at least one binder and / or at least one pasting agent and / or at least one template compound to obtain a mixture; Shaping the resulting mixture by means of at least one suitable method, such as extruding; optionally washing and / or drying and / or calcining the extrudate; optional assembly.

Applying the framework material to at least one optionally porous support material. The material obtained can then be further processed according to the method described above to give a shaped body. Applying the framework material to at least one optionally porous substrate.

Kneading and shaping can be carried out according to any suitable method, as described, for example, in Ullmanns Enzyklopadie der Technischen Chemie, 4th Edition, Volume 2, p. 313 et seq. (1972), the contents of which are incorporated by reference in the context of the present application in its entirety is included.

For example, kneading and / or shaping by means of a combi press, roller press in the presence or absence of at least one binder material, compounding, pelleting, tableting, extrusion, coextrusion, foaming, spinning, coating, granulation, preferably spray granulation, spraying, spray drying may be preferred or a combination of two or more of these methods.

In particular, pellets and / or tablets are produced.

Kneading and / or shaping can be carried out at elevated temperatures, for example in the range from room temperature to 300 ° C. and / or at elevated pressure, for example in the range from atmospheric pressure to several hundred bar and / or in a protective gas atmosphere such as in the presence at least one delig gas, nitrogen or a mixture of two or more thereof.

The kneading and / or shaping is carried out according to a further embodiment with the addition of at least one binder, wherein as a binder in principle any chemical compound can be used which ensures the kneading and / or deformation desired viscosity of the kneading and / or deforming mass. Accordingly, for the purposes of the present invention, binders may be both viscosity-increasing and viscosity-reducing compounds.

Preferred binders include, for example, alumina-containing or alumina-containing binders, as described, for example, in WO 94/29408, silica, as described, for example, in EP 0 592 050 A1, mixtures of silica and alumina, such as For example, in WO 94/13584, clay minerals, as described for example in JP 03-037156 A, for example, montmorillonite, kaolin, bentonite, halloysite, Dickit, Nacrit and anauxite, alkoxysilanes, as described for example in EP 0,102 544 B1, for example tetraalkoxysilanes such as, for example, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, or, for example, trialkoxysilanes, such as, for example, trimethoxysilane, triethoxysilane, tripropoxysilane, tributoxysilane, alkoxytitanates, for example tetraalkoxy titanates such as tetramethoxytitanate, Te- traethoxytitanat, tetrapropoxytitanate, tetrabutoxytitanate, or, for example trialkoxy titanate such as trimethoxytitanate, triethoxytitanate, tripropoxytitanate, tributyl toxytitanat, alkoxyzirconates, for example tetraalkoxyzirconates such as tetramethoxyzirconate, tetraethoxyzirconate Tetrapropoxyzirconate, tetrabutoxyzirconate, or, for example, trialkoxyzirconates such as, for example, trimethoxyzirconate, triethoxyczirconate, tripropoxyzirconate, tributoxyzirconate, silica sols, amphiphilic substances and / or graphites. Particularly preferred is graphite.

As a viscosity-increasing compound, for example, optionally in addition to the above-mentioned compounds, an organic compound and / or a hydrophilic polymer such as cellulose or a CeIIU losederivat such as methylcellulose and / or a polyacrylate and / or a polymethacrylate and / or a polyvinyl alcohol and / or a polyvinylpyrrolidone and / or a polyisobutene and / or a polytetrahydrofuran.

As a pasting agent, inter alia, preferably water or at least one alcohol such as a monoalcohol having 1 to 4 carbon atoms such as methanol, ethanol, n-propanol, iso-propanol, 1-butanol, 2-butanol, 2-methyl-1 - propanol or 2-methyl-2-propanol or a mixture of water and at least one of said alcohols or a polyhydric alcohol such as a glycol, preferably a water-miscible polyhydric alcohol, alone or in admixture with water and / or at least one of said monohydric alcohols are used.

Other additives that can be used for kneading and / or shaping include amines or amine derivatives such as tetraalkylammonium compounds or amino alcohols, and carbonate containing compounds such as calcium carbonate. Such further additives are described for example in EP 0 389 041 A1, EP 0 200 260 A1 or WO 95/19222.

The order of the additives such as template compound, binder, pasting agent, viscosity-increasing substance in the molding and kneading is basically not critical.

According to a further preferred embodiment, the molding obtained according to kneading and / or molding is subjected to at least one drying, which is generally carried out at a temperature in the range of 25 to 300 ° C, preferably in the range of 50 to 300 ° C and more preferably in the range of 100 to 300 ° C is performed. It is also possible to dry in vacuo or under a protective gas atmosphere or by spray drying. According to a particularly preferred embodiment, as part of this drying process, at least one of the compounds added as additives is at least partially removed from the shaped body.

Another object of the invention is the use of a porous organometallic framework for the enrichment of methane in a methane-containing gas mixture.

Examples

Example 1: Adsorptive enrichment of C ₂₊ from a natural gas

A real, high calorific natural gas with the following composition 85.8% methane, 8.76% ethane, 1.58% propane, 0.31% butanes, 0.04% pentanes, 0.01% C ₆₊ , 2.17% CO ₂ and 1, 31% N ₂ (calorific value 11, 79 kWh / Nm ³ ) with an inlet temperature of about 5 ° C at 80 bar over an adsorbent bed with 416 g of Cu-benzenetricarboxylic MOF in the form of 1, 5 mm Guided by strands. CO ₂ , ethane and higher hydrocarbons are adsorptively removed from the natural gas stream. During the adsorption phase, a methane-enriched gas mixture with a calorific value in the range 10.9-11.3 kWh / Nm ^{3 is formed} . When the adsorber is released or backwashed, the substances sorbed on the adsorbent desorb and can be collected as an ethane-rich by-product.

With a methane yield of 80% in the adsorption step, the ethane-rich by-product stream is composed as follows: 57.3% methane, 29.1% ethane, 4.43% propane, 0.85% butane, about 0.15% C ₅ ⁺ , 7.2% CO ₂ and 0.9% N ₂ .

Example 2: Aromatization of an ethane-rich stream

The catalyst used was a Mo- / H-ZSM-5 catalyst (3% by weight Mo, Si: Al ratio of about 20 mol / mol).

This was impregnated in a one-step impregnation by means of an aqueous solution of ammonium heptamolybdate, dried and calcined at 500 ° C.

Approximately 1 g of the powdery catalyst was heated to 500 ° C with He. At this temperature, a mixture consisting of about 5% by volume He and about 95% by volume of the ethane-rich hydrocarbon mixture (about 26% ethane, about 4% propane, the remainder methane) was added and the catalyst was gradually under this mixture heated to 700 ° C. At this temperature (pressure drop across the catalyst about 1 bar) was against external atmosphere, the dehydrogenating A- examined romatisierung at a GHSV of 1000 h ^'1. At the beginning of the reaction, there are 1.75% by volume of benzene in the product stream, after 2.5 h 1.77% by volume.

Comparative Example 3: Aromatization of pure methane Ca. 1 g of the fresh, powdery catalyst from example 2 was heated to 500 ° C. under He. At this temperature, a mixture consisting of about 5% by volume of He and about 95% by volume of methane was added and the catalyst under this mixture gradually heated to 700 ° C. At this temperature, the dehydrogenating aromatization was investigated against external atmosphere (about 1 bar pressure drop over catalyst) at a GHSV of about 1000 h ^-1 .

At the beginning of the reaction, only 0.44% benzene is found in the product stream, after 2.6 h the value drops to 0.12% by volume.

Claims

claims

1. Combined process of depletion or removal of methane from a methane-containing gas mixture A and subsequent reaction of the mixture A to unsaturated compounds comprising the following steps

1) producing a methane-enriched mixture B by contacting the methane-containing gas mixture A with at least one sorbent containing a porous organometallic framework, wherein the framework contains at least one, at least one bidentate organic compound coordinately bound to at least one metal ion;

2) preparing a methane-depleted gas mixture C by desorbing the compounds trapped on the sorbent;

3) reacting the hydrocarbons contained in Mixture C or a part thereof to unsaturated hydrocarbons to obtain a mixture D;

4) optionally separating the mixture D.

2. The method of claim 1, wherein the methane-containing gas mixture is natural gas or contains.

3. The method according to any one of claims 1 or 2, wherein the depletion of the methane by separation of C2-C4 alkanes from the methane-containing gas mixture is carried out by sorption and subsequent desorption.

4. The method according to any one of claims 1 to 3, wherein the methane content before enrichment is at least 50 vol .-% in the methane-containing gas mixture.

5. The method according to any one of claims 1 to 4, wherein the contacting of the gas mixture is carried out with at least one sorbent by continuous adsorption.

6. The method according to any one of claims 1 to 5, wherein in step 3) a dehydrating aromatization of the mixture contained in C, saturated and unsaturated hydrocarbons or a part thereof in the presence of a catalyst to aromatic hydrocarbons, a mixture D is obtained and the separation of the mixture D takes place in a blending mixture E, which is the main part of the resulting H ₂ and the unreacted hydrocarbons contains, and in at least one high-boiling mixture F, which contains the majority of the unsaturated hydrocarbons formed.

7. The method of claim 6, wherein the dehydrogenating aromatization is carried out under oxidative conditions.

8. The method according to any one of claims 1 to 5, wherein in step 3) a reaction of the mixture contained in the mixture C, saturated and unsaturated hydrocarbons or a part thereof to ethylene, a mixture D is obtained and the separation of the mixture D is carried out by distillation , preferably in one

C1 / C2 mixture E 'and a mixture F' containing higher hydrocarbons.

9. The method according to any one of claims 1 to 8, wherein in step 3) a reaction of the mixture contained in mixture C, saturated and unsaturated hydrocarbons or a part thereof as described in any one of claims 7 or 8 is carried out, then in a step 3i) a Reaction is carried out to ethylbenzene and the separation of the ethylbenzene from the other constituents by distillation.

10. The method according to any one of claims 1 to 9, characterized in that in the organometallic framework material, an acid from the group isophthalic acid, terephthalic acid, 2,5-dihydroxyterephthalic acid, 1, 2,3-benzenetricarboxylic acid, 1, 3,5- Benzoltricarbonsäure, 2,2'-bipyridine-5,5'-dicarboxylic acid, 1, 4-naphthalenedicarboxylic acid, 1, 5-naphthalenedicarboxylic acid or 2,6-naphthalenedicarboxylic acid is used.

1 1. The method according to any one of claims 1 to 10, characterized in that in the organometallic framework material, a metal ion from the group Zn ²⁺ , Al ³⁺ ,

Co ²⁺ , Co ³⁺ , Fe ³⁺ and Cu ^{2+ is} present ..