CA1111074A

CA1111074A - Process for preparing aromatic hydrocarbons

Info

Publication number: CA1111074A
Application number: CA310,511A
Authority: CA
Inventors: Lambert Schaper; Swan T. Sie
Original assignee: Shell Canada Ltd
Current assignee: Shell Canada Ltd
Priority date: 1977-10-26
Filing date: 1978-09-01
Publication date: 1981-10-20
Also published as: FR2407190B1; NL7711719A; IT1099503B; BE871276A; FR2407190A1; AU4100678A; IT7829061A0; AU521103B2; GB2006819B; DE2846254A1; JPS5470230A; ZA785979B; GB2006819A

Abstract

A B S T R A C T

Process for preparing aromatic hydrocarbons. A gas with a H2/CO molar ratio less than 1.0, is contacted with a trifunctional catalyst containing one or more metals catalyzing the conversion of a H2/CO mixture into hydro-carbons and/or oxygen-containing hydrocarbons, one or more metals catalyzing the water gas shift reaction and a crystalline iron silicate.

Description

PROCESS FOR PREPARINC ARO~IATIC IIYDROCARBONS
The invention relates to a process for preparing aromatic hydro-carbons by catalytic reaction of carbon monoxide with hydrogen.
Hydrocarbon mixtures boiling in the gasoline range can be obtained, for instance, by straight-run distillation of crude mineral oil, by conver-sion of heavier mineral oil fractions, for instance, by catalytic cracking, thermal cracking and hydrocracking and by conversion of lighter mineral oil fractions, for instance, by alkylation. To improve the octane number of the hydrocarbon mixtures thus obtained, they are often subjected to catalytic reforming, as a result of which the aromatics content increases.
; In view of the increasing need of gasoline and the decreasing re-serves of mineral oil there is a great interest in processes permitting the conversion in an economically justified way of carbon-containing materials not based on mineral oil, such as coal, into hydrocarbon mixtures boiling in `the gasoline range. It is desirable that these hydrocarbon mixtures should have a sufficiently high octane number, as a result of which they are suit-able for use as gasoline without any further refining.
It is known that carbon-containing materials, such as coal, can be converted in a relatively simple way into mixtures of carbon ~onoxide and hydrogen by steam gasification. It is further known that mixtures of carbon monoxide and hydrogen IYhose H2/CO molar ratio is more than 1.0 can be con-verted in good yield into mixtures of hydrocarbons by contacting the gas mixtures with suitable catalysts. Attempts to achieve a commercially attrac-tive process for the preparation of gasoline from carbon-containing mate-rials, such as coal, by combining the two processes have met with serious objections. These objections are in the first place connected with the com-position of the mixture of carbon monoxide and hydrogen that is obtained in the steam gasificat:ion and further with the composition of the mixture of ... . . .

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hydrocarbons formed in the conversion of the mixture of carbon monoxide and hydrogen.
It has been found that in the steam gasification for obtaining a high yield of a mixture of carbon monoxide and hydrogen and for suppressing the formation of methane, tarry products and phenols, tempera-tures higher than 1000C should be used. It has further been found that the H2/C0 molar ratio in the product obtained in the steam gasification is highly dependent - on the temperature used and that at temperatures higher than 1000C gas mix-`~ tures are obtained in which the H2/C0 molar ratio is smaller than 1Ø Such10 gas mixtures are less suitable for conversion in the second stage of the above-mentioned combination process in which gas mixtures with a H2/C0 molar ratio above 1.0 are desired. An intermediate increase of the H2/C0 molar ratio to above 1.0 by applying the water gas shift reaction to these gas mixtures with low H2/C0 ratio is not suitable for commercial use, because this step implies that the gas with increased H2/C0 molar ratio thus ob-tained should then be subjected to an expensive gas separation treatment to remove carbon dioxide, before the gas can be converted in the second stage .~ of the combination process.
As regards the composition of the mixture of hydrocarbons formed 20 in the conversion of the mixture of carbon monoxide and hydrogen it is noted , that this mixture has a very wide molecular weight distribution and that it contains hardly any aromatics. This means that only part of this mixture consists of hydrocarbons boiling in the gasoline range and that, moreover, before this part can be used as gasoline it first has to be subjected to a catalytic reforming treatment to increase the aromatics content.
: The Applicant has carried out an extensive investigation to ex-amine to what extent it is possible to prepare from mixtures of carbon mon-oxide and hydrogen such as they are obtained in the high-temperature steam

- 2 -gasification of carbon-containing materials such as coal, aromatic hydro-carbon mixtures with a high octane number that are suitable for use as gas-oline without any further refining. In the investigation emphasis has been placed on the implementation of this conversion in one stage.
It has been found that the above-mentioned requirements can indeed be met by contacting the gas mixture with a catalyst which combines three functions. In the first place the catalyst should comprise one or more metal components having catalytic activity for the conversion of a H2/C0 mixture into hydrocarbons and/or oxygen-containing hydrocarbons. ~he cat-. 10 alyst should further contain a crystalline silicate which a) is thermally stable to temperatures higher than 600C, b) is capable of absorbing, after dehydration at 400C in vacuum, more than

3 %w water at 25C and saturated water vapour pressure, and c) has, in dehydrated form, the following overall composition, expressed in moles of the oxides.

)( )2/n l a Fe203. b A1303. c Ga203 ~ .y~d SiO2- e GeO2), where R = one or more mono- or bivalent cations, a > 0.1, b > 0.
c > O.
a + b + c = 1.
y > 10.
d > 0.1, e > 0.
d + e = 1, and n = the valency of R.
Finally, the catalyst should contain one or more metal components having X

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catalytic ac-tivity for the water gas shift reaction.
The present patent application therefore relates to a process for preparing aromatic hydrocarbons by catalytic reaction of carbon monoxide with hydrogen> in which process a mixture of carbon monoxide and hydrogen, whose ~2/C0 molar ratio is less than 1.() is convertecl in one step into an aromatic hydrocarbon mixture by contacting the gas mixture with a trifunc-tional catalyst containing one or more metal components having catalytic activity for the conversion of a H2/C0 mixture into hydrocarbons and/or oxygen-containing hydrocarbons, one or more metal components having cata-lytic activity for the water gas shift reaction and a crystalline silicate as defined hereinbefore.

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` The process according to the invention starts from a mixture of carbon monoxide and hydrogen whose H2/CO molar ratio is less than 1Ø As ~:~ was mentioned earlier, such a mixture can be readily prepared by steam gas-"
ification of a carbon-containing material at a high temperature. Examples of such materials are brown coal, anthracite, coke, crude mineral oil and fractions thereof, as well as oils extracted from tar sand and bituminous shale. During the steam gasification the feed, in finely divided form, is converted with steam and oxygen or air, if desired enriched with oxygen, into a gas mixture containing, inter alia, hydrogen, carbon monoxide, carbon dioxide, nitrogen and water. The steam gasification is preferably carried out at a temperature between 1000 and 2000 C and a pressure between 10 and 50 bar. In order to be able to remove contaminants such as ash, carbon-con-taining material and hydrogen sulphide from the gas obtained in the steam gasification, which has a temperature higher than 1000C. this gas should first be cooled down to a temperature between 100 and 200C. This cooling can very suitably be effected in a boiler in which steam is generated with the aid of the waste heat. The cooled gas can be freed from nearly all , _ ~ _ .;

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solid components by washing it with water. After this washing treatment, during which the temperature of the gas has fallen to 20-80C, the gas is further purified by removal of hydrogen sulphide and carbon dioxide. This may very suitably be effected with the aid of the ADIP process or the SUL-FINOL process.
~ he trifunctional catalysts which are used in the process accord-ing to the invention contain, in addition to the metal components, a crys-talline silicate of a special class. These silicates effect a high conver-sion of aliphatic hydrocarbons into aromatic hydrocarbons in commerciallydesirable yields and they are in general very active in conversion reactions in which aromatic hydrocarbons are involved.
In the process according to the invention preference is given to the use of silicates in which no gallium or germanium are present, in other words: silicates of which, in the above-mentioned overall composition, c and e are 0. Such silicates are the subject of Netherlands patent applica-tion No. 7,613,957. Further, in the process according to the invention preference is given to the use of silicates of which, in the above-mentioned overall composition, a is greater than 0.3 and in particular of which a is greater than 0.5. Particular preference is given to silicates in which no aluminium is present, in other words: silicates of which in the above-men-tioned overall composition b is 0. It should be noted that in the silicates which are used in the process according to the invention, y is preferably less than 600 and in particular less than 300. Finally, in the process according to the invention preference is given to silicates whose X-ray powder diffraction pattern has, inter alia, the reflections given in Table A
of Netherlands Patent Application 7,613,957, published June 20, 1978.
The trifunctional catalysts which are used in the process accord-ing to the invention contain one or more metal components having catalytic ' , ' ~ ~' ', , - ' : : ' 7~6 activity for the conversion of a H2/CO mixture into hydrocarbons and/or oxygen-containing hydrocarbons, one or more metal components having cata-: lytic activity for the water gas shift reaction and a crystalline silicate such as defined hereinbefore having catalytic activity for the conversion of acyclic hydrocarbons ancl/or oxygen-containing acyclic hydrocarbons into an aromatic hydrocarbon mixture boiling in the gasoline range. The ratio in which the three catalytic functions are present in the catalyst may vary within wide limits and is substantially determined by the activity of each of the catalytic functions. For, in the process according to the invention ; 10 the object is that of the acyclic hydrocarbons and/or oxygen-containing acyclic hydrocarbons formed under the influence of the first catalytic func-tion, as much as possible is converted under the~influence of a second cata-lytic function into an aromatic hydrocarbon mixture boiling in the gasoline .- range, and that of the water liberated in the conversion of the mixture of carbon monoxide and hydrogen into hydrocarbons and/or in the conversion of oxygen-containing hydrocarbons into an aromatic hydrocarbon mixture, as much as possible reacts under the influence of a third catalytic function with the carbon monoxide present in an excess amount in the mixture of carbon monoxide and hydrogen with formation of a mixture of hydrogen and carbon di-oxide. In the composition of an optimum trifunctional catalyst to be used in the process according to the invention, which catalyst contains a given quantity of a first catalytic function having a given activity, it is there-fore possible to do with less of the other catalytic functions according as these are more active.
Although the catalysts according to the invention are described in this patent application as catalysts containing one or more metal components having catalytic activity for the conversion of a 112/C0 mixture into hydro-carbons and/or oxygen-containing hydrocarbons and one or more metal compon-' " ' ' ` ~ ` ~

3i74 ents having catalytic activity for the water gas shiEt reaction, this means in no way that metal components each having in themselves one of the two catalytic functions should always separately be present in the catalysts according to the invention. For~ it has been found that metal components and combinations of metal components having catalytic activity for the con-version of a ~12/C0 mixture into substantially oxygen-containing hydrocarbons as a rule also have sufficient catalytic activity for the water gas shift reaction, so that in such a case incorporation of one metal component or one combination of metal componen~s into the catalysts according to the inven-tion will suffice. Examples of such metal components are the metals chosenfrom the group formed by the metals zinc, copper and chromium. When use is made of trifunctional catalysts according to the invention containing these metals, preference is given to catalysts containing combinations of at least two of these metals, for instance the combination zinc-copper, zinc-chromium or zinc-copper-chromium. Particular preference is given to a trifunctional catalyst containing, in addition to the crystalline silicate the metal com-bination zinc-chromium. Metal components and combinations of metal compon-ents having catalytic activity for the conversion of a H2/C0 mixture into substantially hydrocarbons have as a rule no or insufficient activity for the water gas shift reaction. When use is made of such metal components or combinations of metal components in the catalysts according to the inven-tion, one or more separate metal components having catalytic activity for the water gas shift reaction should therefore be incorporated therein.
The trifunctional catalysts which are used according to the inven-tion are preferably composed of two or three separate catalysts, which will for convenience be designated catalysts X, Y and Z. Catalyst X is the cata-lyst containing the metal components having catalytic activity for the con-version of a H2/C0 mixture into hydrocarbons and/or oxygen-containing hydro-,' ' ', ' , '. ~ .

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carbons. Catalyst Y is the crystalline silicate. Catalyst Z is the cata-lyst containing the metal component having catalytic activity for the water - gas shift reaction. As has been explained hereinbefore the use o:E a Z-cata-lyst may be omitted in some cases.
If as the X-catalyst a catalyst is used whicll is capable of con-verting a H2/CO mixture into substantially oxygen-containing hydrocarbons, preference is given to a catalyst which is capable of converting the H2/CO
mixture into substantially methanol and/or dimethyl ether. For the conver-sion of a H2/CO mixture into substantially methanol, catalysts containing . 10 the metal combinations mentioned hereinbefore are very suitable. If de-,. sired, the said metal combinations may be emplaced on a carrier material.
'- By introducing an acid function into these catalysts, for instance by em-placing the metal combination on an acid carrier, it may be effected that . apart from the conversion of the H2/CO mixture into methanol a considerable part of the mixture will be converted into dimethyl ether.
X-catalysts which are capable of converting a H2/CQ mixture into substantially hydrocarbons are referred to in the literature as Fischer-Tropsch catalysts. Such catalysts often contain one or more metals of the iron group or ruthenium together with one or more promoters to increase the ; activity and/or selectivity and sometimes a carrier material such as kieselguhr. They can be prepared by precipitation, melting and by impreg-~ nation. The preparation of the catalysts containing one or more metals of ; the iron group, by impregnation, takes place by impregnating a porous car-rier with one or more aqueous solutions of salts of metals of the iron group and, optionally, of promoters, followed by drying and calcining the composi-tion. If in the process according to the invention use is made of a cata-lyst combination in which catalyst X is a Fischer-Tropsch catalyst, it is preferred to choose for this purpose an iron or cobalt catalyst, in partic-: - 8 -'' X ' .'~

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ular such a catalyst which has been prepared by impregnation. Very suitable Fischer-Tropsch catalysts for use in the catalyst combinations according to the invention are the catalysts preparecl by impregnation according to the Netherlands Patent Application 7,612,~l60, published May 12, 1978. The cata-lysts concerned contain per 100 pbw carrier 10-75 pbw of one or more metals of the iron group, together with one or more promoters in a quantity of 1-- 50% of the quantity of metals of the iron group present on the catalyst, which catalysts have such a specific average pore diameter (p) of at most 10,000 nm and such a specific average particle diameter (d) of at most 5 mm, the quotient p/d is more than 2 (p in nm and d in nm).
If in the process according to the invention the object is to use a catalyst combination of which X is a Fischer-Tropsch iron catalyst, it is preferred to choose an iron catalyst containing a promoter combination con-sisting of an alkali metal, a metal that is easy to reduce, such as copper or silver and, optionally, a metal that is hard to reduce, such as aluminium or zinc. A very suitable iron catalyst for the present purpose is a cata-lyst prepared by impregnation containing iron, potassium and copper on sil-ica as the carrier. If in the process according to the invention the object is to use a catalyst combination of which X is a Fischer-Tropsch cobalt catalyst, it is preferred to choose a cobalt catalyst containing a promoter combination consisting of an alkaline-earth metal and thorium, uranium or cerium. A very suitable Fischer-Tropsch cobalt catalyst for the present purpose is a catalyst prepared by impregnation containing cobalt, magnesium and thorium on silica as the carrier. Other very suitable Fischer-Tropsch cobalt catalysts prepared by impregnation are catalysts containing, in addi-tion to cobalt, one of the elements chromium, titanium, zirconium and zinc on silica as the carrier. If desired, it is also possible to use in the process according to the invention catalyst combinations containing an X-_ g _ X

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catalyst, which is capable of converting a H2CO mixture into a mixture con-taining both hydrocarbons and oxygen-containing hydrocarbons in comparable quantities. As a rule, such a catalyst has sufficient catalytic activity for the water gas shift reaction, so that -the use of a Z-catalyst in the combination can be omitted. An example of an X-catalyst of thi-s type is an iron-chromium oxide catalyst. If desired, it is also possible to use in the process according to the invention catalyst combinations containing two or more X-catalysts, for instance in addition to a catalyst of the X-type which is capable of converting a H2/CO mixture into substantially hydrocarbons, a second catalyst of the X-type which is capable of converting a H2CO mixture into substantially oxygen-containing hydrocarbons.
Z-catalysts which are capable of converting a H2O/CO mixture into a H2/CO2 mixture are referred to in the literature as CO-shift catalysts.
Such catalysts often contain one or more metals of the group formed by iron, chromium, copper, zinc, cobalt, nickel and molybdenum as the catalytically active component, either as such, or in the form of their oxides or sul-phides. Examples of suitable CO-shift catalysts are the mixed sulphidic cat-alysts according to the Netherlands Patent Application 7,305,340 published October 21, 1974, Netherlands Patent Application 7,304,793, published October 9, 1974 and Canadian Patent Application No. 287,679. If in the pro-cess according to the invention use is made of a catalyst combination in which a Z-catalyst is present, it is preferred to choose a catalyst which contains both copper and zinc, in particular a catalyst in which the Cu/Zn atomic ratio lies between 0.25 and 4Ø
In the trifunctional catalysts the catalysts X, Y and, optionally, Z may be present as a mixture, in which, in principle, each particle of cata-lyst X is surrounded by a number of particles of catalyst Y and, optionally, catalyst Z and conversely. If the process is carried out with the use of a X

fixed catalyst bed, this bed may be built up of alternate layers of parti-` cles of catalysts X, Y and, optionally, Z. If the two or three catalysts are used as a mixture, this mixture may be a macromixture or a micromixture.
~` In the first case the trifunctional catalyst consists of two or three kinds of macroparticles of which one kind is completely made up of catalyst X, the ;.
second kind completely of catalyst Y and, optionally, a third kind complete-ly of catalyst Z. In the second case the trifunctional catalyst consists of one kind of macroparticles, each macroparticle being made up of a large num-ber of microparticles of each of the catalysts X, Y and, optionally, Z.
Trifunctional catalysts according to the invention in the form of micromix-tures may be prepared, for instance, by thoroughly mixing a fine powder of catalyst X with a fine powder of catalyst Y and, optionally, with a fine pow-der of catalyst Z and shaping the mixture to larger particles, for instance, by extruding or pelleti~ing. In the process according to the invention it is preferred to use trifunctional catalysts in the form of micromixtures.
The trifunctional catalysts which are used according to the inven-tion may also have been prepared by incorporating the metal components hav-ing catalytic activity for converting a H2JCO mixture into hydrocarbons and/
or oxygen-containing hydrocarbons and, optionally, the metal components hav-ing catalytic activity for the water gas shift reaction into the crystalline silicate, for instance by impregnation or by ion exchange.
The crystalline silicates which are used in the trifunctional cat-alysts according to the invention are usually prepared from an aqueous mix-ture as the starting material which contains the following compounds in a given ratio; one or more compounds of an alkali or alkaline-earth metal, one or more compounds containing a mono- or bivalent organic cation or from which such a cation is formed during the preparation of the silicate, one or more silicon compounds, one or more iron compounds, and, optionally, one or ,.. .
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more aluminium, gallium and/or germanium compounds. The preparation is ef-fected by maintaining the mixture at elevated temperature until the silicate has been formed and then separating the crystals of the silicate from the ~;
mother liquor. The silicates thus prepared contain alkali and/or alkaline-earth metal ions and mono- and/or bivalent organic cations. Before being .:~` used in the trifunctional catalysts according to the invention at least part of the mono- and/or bivalent organic cations introduced during the preparation are preferably converted into hydrogen ions, for instance by calcining and at least part of the exchangeable mono- and/or bivalent . 10 cations introduced during the preparation are preferably replaced by other ions, in particular hydrogen ions, ammonium ions and/or ions of the rare-earth metals. The crystalline silicates used in the trifunctional catalysts . according to the invention preferably have an alkali metal content of less than 1 %w and in particulàr of less than 0.05 %w. If desired, a binder ma-terial such as bentonite or kaolin may be incorporated in the trifunctional catalysts.
The process according to the invention preferably starts from a mixture of carbon monoxide and hydrogen whose H2/C0 molar ratio is more than 0.4.
The process according to the invention is preferably carried out at a temperature of from 200 to 500C and in particular of from 300 to 450C, a pressure of from 1 to 150 bar and in particular of from 5 to 100 bar and a space velocity of from 50 to 5000 and in particular of from 300 to 3000 Nl gas/l catalyst/hour.
~: The process according to the invention can very suitably be car-ried out by passing the feed in upward or in downward direction through a vertically disposed reactor in which a fixed or a moving bed of the trifunc-tional catalyst concerned is present. The process may, for instance, be . ~r . .

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carried out in the so-called fixed-bed operation, in bunker-flow operation or in ebulated-bed operation. It is preferred to use catalyst particles then with a diameter between 1 and 5 mm. If desired, the process may also be carried out in fluidized-bed operation or with the use of a suspension of the catalyst in a hydrocarbon oil~ It is preferred to use catalyst par-ticles then with a diameter between 10 and 150 ~m.
The invention will now be explained with reference to the follow-ing examples~
Example I
A crystalline iron silicate ~silicate A) was prepared as follows.
A mixture of Fe(N03)3~ SiO2~ NaN03 and [(C3117)4N]OH in water with the molar omposition Na 0- 1-5[(C3H7)4N]20- 0-~25 Pe23 2 2 heated for 48 hours in an autoclave at 150C under autogenous pressure.
After the reaction mixture had cooled down, the silicate formed was filtered - off, washed with water until the pH of the wash water was about 8 and dried for two hours at 120C. Silicate A thus prepared had the following chemical composition 0.8[(C3H7)4N/2o. 0.3 Na20. Fe203 2 2 The silicate had an X-ray powder diffraction pattern substantially as given in Table B of Netherlands patent application No. 7,613,957. The silicate was thermally stable to temperatures higher than 900C and was cap-able, after dehydration at 400C, to absorb in vacuum 7 ~w water at 25C and saturated water vapour pressure. With silicate A as the starting material silicate B was prepared by, successively, calcining silicate A at 500 C, boiling with 1.0 molar NH~1N03 solution, washing with water, boiling again with 1.0 molar NH4N03 solution and washing, drying for two hours at 120C
and calcining for four hours at 500C.
Example II

A crystalline silicate (silicate C) was prepared in substantially ~Y~

the same way as silicate A, the difference being that in the present case the starting material was an aqueous mixture which contained, in addition to Fe(NO3)3, Al~NO3)3 and which had tlle following molar composition:
Na2 4-5[(C3ll7)4N]2o 0.35 A1203 0.15 Fe2O3. 29.1 SiO2. 468 H20.
Silicate C thus prepared had the following chemical composition:
0.35[(C3~17)4N]20. 0-2 Na20. 0.15 Fe203. 0.35 A1203. 31 SiO2. 9 H20.
The silicate had an X-ray powder diffraction pattern substantially as given in Table B of Netherlands Patent Applica~ion 7~613,957, published June 20, 1978. The silicate was thermally stable to temperatures higher than 1000C and was capable, after a dehydration at 400C in vacuum, of ab-sorbing 8 %w water at 25C and saturated water vapour pressure. With sili-cate C as the starting material silicate D was prepared in the same way as described for the preparation of silicate B from silicate A.
Example III
A catalyst was prepared by mixing a ZnO-Cr203 composition with the crystalline iron silicate B in a weight ratio of 3:1. Both materials were present in the catalyst in the form of particles with a diameter of 0.15-0.3 mm. The ZnO-Cr203 composition used catalyses both the reduction of C0 to methanol and the water gas shift reaction. The catalyst obtained by mixing was tested for the one-stage preparation of an aromatic hydrocarbon mixture starting from a mixture of carbon monoxide and hydrogen. The testing was carried out in a 50-ml reactor, in which a fixed catalyst bed having a vol-ume of 7.5 ml was present. A mixture of carbon monoxide and hydrogen with a H2/C0 molar ratio of 0.5 was passed across the catalyst at a temperature of 37iC, a pressure of 60 bar and a space velocity of 1000 Nl gas/l cata-lyst/h. The results of this experiment are given below C0 conversion, % 50 ll2 conversion, % 53 ~,~

Product composition, %w on Cl+ product `. Cl S

: C
C~, 10 C5 product composition, %w on C5 product paraffins + olefins 20 naphthenes 27 aromatics 53 Example IV
- A catalyst was prepared by mixing the ~nO-Cr203 composition of ex-ample III with the crystalline iron-aluminium silicate D in a weight ratio of 5:1. Both materials were present in the catalyst in the form of par-ticles with a diameter of 0.15-0.3 mm. This catalyst was tested for the one-stage preparation of an aromatic hydrocarbon mixture starting from a mixture of carbon monoxide and hydrogen with a H2/C0 molar ratio of 0.5.
The testing was carried out in substantially the same way as described in example III, the differences being that in the present case a temperature of 350C and a pressure of 80 bar were used. The results of this experiment are given below C0 conversion, % 54 H2 conversion, % 59 Product composition, %w on C product ' 1 ' C 2 ; C2 2 c3 15 10 . .
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naphthenes 20 aromatics 62 .: ' -::
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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for preparing aromatic hydrocarbons by catalytic reaction of carbon monoxide with hydrogen characterized in that a mixture of carbon monoxide and hydrogen whose H2/CO molar ratio is less than 1.0 is converted in one step into an aromatic hydrocarbon mixture by contacting the gas mixture with a trifunctional catalyst containing one or more metal components having catalytic activity for the conversion of a H2/CO mixture into hydrocarbons and/or oxygen-containing hydrocarbons one or more metal components having catalytic activity for the water gas shift reaction and a crystalline silicate which a) is thermally stable to temperatures higher than 600°C
b) is capable of absorbing after dehydration at 400°C in vacuum more than 3%w water at 25°C and saturated water vapour pressure and c) has, in dehydrated form, the following overall composi-tion, expressed in moles of the oxides.
(1.0 + 0.3)(R)2/nO./a Fe2O3. b A12O3. c Ga2O3 /.
y (d SiO2. e GeO2), where R=one or more mono or bivalent cations, a ? 0.1.
b ? 0.
c ? 0.
a + b + c = 1.
y ? 10.
d ? 0.1.

e ? 0.
d + e = 1, and n = the valency of R

2. A process according to claim 1, characterized in that the trifunctional catalyst is composed of three separate catalysts of which the first catalyst (catalyst X) contains the metal compon-ents having catalytic activity for the conversion of a H2/CO mix-ture into substantially hydrocarbons, the second catalyst (cata-lyst Y is the crystalline silicate and the third catalyst (catalyst Z) contains the metal components having catalytic activity for the water gas shift reaction.

3. A process according to claim 2, characterized in that catalyst X is an iron or cobalt catalyst.

4. A process according to claim 2, characterized in that catalyst Z is a catalyst which contains both copper and zinc.

5. A process according to claim 2 characterized in that a trifunctional catalyst is used which consists of one kind of macroparticles, each macroparticle being built up of a large number of microparticles of each of the catalysts X, Y, and, optionally Z.

6. A process according to any of claims 1 to 3 characterized in that it is carried out at a temperature of from 200 to 500°C, a pressure of from 1 to 150 bar and a space velocity of from 50 to 5000 N1 gas/1 catalyst/h.