NZ198726A - Preparation of aromatic hydrocarbon mixture from hydrogen and carbon monoxide - Google Patents

Description

New Zealand Paient Spedficaiion for Paient Number 1 98726 198726 Priorjly Zi.Uis): Comri.oto Cn-uciffcstlon Filed^ C5sss: <MW£?7<£7..~ - Publication Cats: .5.1.4^.^???. f\ 0. Journal, Fu'o: ... IJUpJQ No.: Date: COMPLETE SPECIFICATION A PROCESS FOR THE PREPARATION OF HYDROCARBONS XXI We, SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V. Carel van Bylandtlaan 30, The Hague, the Netherlands, a Netherlands Company hereby declare the invention for which3*!*/ we pray that a patent may be granted toXBCe/us, and the method by which it is to be performed, to be particularly described in and by the following statement: - - 1 - (followed by page la) .198726 1 <a_ A PROCESS FOR THE PREPARATION OP IIYDnOCAItDONS The invention relates to a process for the preparation of an aromatic hydrocarbon mixture from a mixture of carbon monoxide and hydrogen.

Mixtures of carbon monoxide and hydrogen may be 5 converted into aromatic hydrocarbon mixtures using a mixture of two catalysts, of which one has the capability of catalyzing the conversion of an I^/CO mixture into acyclic oxygen-containing hydrocarbons, and the other is a crystalline iron or aluminium silicate having the 10 capability of catalyzing the conversion of acyclic oxygen-containing hydrocarbons into aromatic hydrocarbons . The said crystalline iron and aluminium silicates are characterized in that after one hour's calcining in air at 500°C they have the following 15 properties: (a) thermally stable up to a temperature above 600°C, (b) an X-ray powder diffraction pattern showing the reflections given in Table A, and (c) in the formula which gives the composition of the 20 silicate, expressed in moles of the oxides, and in which, in addition to oxides of hydrogen, alkali metal and silicon, an oxide of a trivalent SI98726 2 metal A chosen from A1 and Fe is present, the Si02/A20^ molar ratio is more than 10.

TABLE A d(2) Relative intensity d(S) Relative intensity 11.1 100 3.84 (D) 57 .0 (D) 70 3-70 (D) 31 8.93 1 3.63 16 7.99 1 3.47 < 1 7.42 2 3.43 6.68 7 3.34 2 6.35 11 3-30 .97 17 3.25 1 .70 7 3.05 8 .56 2.98 11 .35 2 2.96 3 4.98 (D) 6 2.86 2 4.60 4 2.73 2 4.35 2.60 2 4.25 7 2.48 3 4.07 2 2.40 2 4.00 4 (D) = doublet 198726 3 The crystalline silicates which are used in the catalyst mixtures are prepared from an aqueous starting mixture containing the following compounds: one or more compounds of an alkali metal(M), a tetrapropylammonium 5 compound, one or more silicon compounds and one or more iron or aluminium compounds.

The preparation of the crystalline silicates takes place by maintaining the mixture at elevated temperature until the silicate has been formed, separating this from 10 the mother liquor and calcining it. In the aqueous mixture from which the silicates are prepared, the various compounds should be present in the following ratios, expressed in moles of the oxides: M20 : Si02 = 0.01 - 0.35, [(C3H7)4N]20 : Si02 = 0.01 - 0.4, Si02 : A20^ > 10, and H20 : Si02 =5-65.

The Applicant has carried out a comparative investigation concerning the use of the crystalline iron 20 and aluminium silicates prepared as described above, as the catalyst component in the above-mentioned catalyst mixtures to be used for the preparation of an aromatic hydrocarbon mixture from an H2/C0 mixture. It was found then that the use of iron silicates is to be preferred 25 to the use of aluminium silicates, because the catalyst mixtures containing an iron silicate show a considerably 98726 higher selectivity. Although the catalyst mixtures containing an iron silicate show a very acceptable behaviour when used in the conversion of an f^/CO mixture into an aromatic hydrocarbon mixture, there is neverthe-5 less a need to improve this behaviour still further, in particular as regards the stability and the production of durene. The latter aspect is important in particular if the aromatic hydrocarbon mixtures prepared are to be used as gasoline. Considering the high melting point of 10 durene, it is desirable that its concentration in the aromatic hydrocarbon mixture be as low as possible.

The Applicant has carried out an investigation to find out whether by changing the preparation of the crystalline iron silicates, products may be obtained 15 which, when used as catalyst component in the above-mentioned catalyst mixtures, can change the behaviour of these catalyst mixtures into the desired direction. It was found then that by replacing in the aqueous mixture from which tie crystalline iron and aluminium 20 silicates are prepared the tetrapropylammonium compound with a tetrabutylammonium compound or with a tetra-butylphosphonium compound, crystalline silicates with a different structure are obtained. After one hour's calcining in air at 500°C the crystalline iron and 25 aluminium silicates thus prepared have an X-ray powder diffraction pattern showing the reflections given in Table B. 198726 Comparison of the X-ray powder diffraction patterns given in the Tables A and B shows the following differences : (a) In Table B the following reflections are missing: 8.93; 7.99; 5.35; 4.07; 3.43; 3.25; 2.96; 2.73. (b) In Table A the following reflections are much more intensive than in Table B: 6.35; 5.70; 4.25; 4.00; 3.63. (c) In Table A the following reflections are doublets, whereas they are singlets in Table B: .0; 3-84; 3 .70.

TABLE B d(S) Relative intensity d(2) Relat: inten 11.1 100 3.84 65 .0 70 3.70 7.42 2 3.63 < 2 6.68 3.47 2 6.35 2 3.34 1 .97 16 3.30 4 .70 < 1 3-05 .56 8 2.98 9 4.98 6 2.86 1 4.60 3 2.60 2 4.35 2.48 3 4.25 < 1 2.40 2 4.00 < 1 198726 6 The Applicant has found that if in a catalyst mixture containing an iron silicate which after one hour's calcining in air at 500°C shows an X-ray powder diffraction pattern as given in Table A the silicate is 5 replaced with an iron silicate which after one hour's calcining in air at 500°C shows an X-ray powder diffraction pattern as given in Table B, a catalyst mixture is obtained which, when it is used in the preparation of an aromatic hydrocarbon mixture from an Hg/CO mixture, 10 shows a considerably higher stability and a considerably lower durene production. This is highly surprising, considering the fact that if in a catalyst mixture containing an aluminium silicate which after one hour's calcining .in air at 500°C shows an X-ray powder diffraction pat-15 tern as given in Table A, the silicate is replaced by an aluminium silicate which after one hour's calcining in air at 500°C shows an X-ray powder diffraction pattern as given in Table B, a catalyst mixture is obtained which, when it is used in the preparation of an 20 aromatic hydrocarbon mixture from an I^/CO mixture, shows a considerably lower stability and a considerably higher durene production.

The present patent application therefore relates to a process for the preparation of an aromatic hydro-25 carbon mixture in which an I^/CO mixture is contacted with a mixture of two catalysts of which one has the 7 198726 capability of catalyzing the conversion of an E^/CO mixture into acyclic oxygen-containing hydrocarbons and the other is a crystalline iron silicate which after one hour's calcining in air at 500°C has the following 5 properties: (a) thermally stable up to a temperature above 600°C, (b) an X-ray powder diffraction pattern showing the reflections given in Table B, and (c) in the formula which gives the composition of the 10 silicate, expressed in moles of the oxides, the SiOg/Fe^^ molar ratio is more than 10.

The process according to the invention starts from an H2/C0 mixture. Such a mixture can very suitably"be prepared by steam gasification of a carbon-containing 15 material. Examples of such materials are brown coal, anthracite, coke, crude mineral oil and fractions thereof and oils produced from tar sand and bituminous shale. The steam gasification is preferably carried out at a temperature between 900 and 1500°C and a pres-20\ sure between 10 and 50 bar. In the process according to \ the invention the preferred starting material is an H2/C0 mixture whose molar ratio lies between 0.25 and 1.0.

The process according to the invention is prefer-25 ably carried out at a temperature of 200-500°C and in particular of 300-U50°C, a pressure of 1-150 bar and 198726 8 in particular of 5-100 bar and a space velocity of 50-5000 and in particular of 300-3000 N1 gas/1 catalyst/h.

In the process according to the invention a 5 mixture of two catalysts is used, which for convenience will be designated catalyst X and catalyst Y. Catalyst X is the one capable of catalyzing the conversion of an I^/CO mixture into acyclic oxygen-containing hydrocarbons and catalyst Y is the crystalline iron silicate. 10 Catalysts that are preferably used as X-catalysts are those which are capable of converting an ^/CO mixture into substantially methanol and/or dimethyl ether. Very suitable for the present purpose are catalysts that contain zinc together with chromium. When using such a 15 catalyst, it is preferred to choose one in which the atomic percentage of zinc, based on the sum of zinc and chromium, is at least 60% and in particular 60-80%. Preferred catalyst mixtures are those containing per part by volume of catalyst Y, 1-5 parts by volume of 20 catalyst X.

Although the crystalline silicates used in the process according to the invention are designated iron silicates, they may contain, in addition to iron, a small amount of aluminium. The silicon compounds which 25 are suitable for the preparation of crystalline silicates on a technical scale from an economical point of view, 9 198726 contain as a rule a small amount of aluminium as contaminant. As a rule, this aluminium is found, at least partly in the silicate prepared.

The iron silicates used in the process according 5 to the invention, are prepared from an aqueous mixture containing one or more alkali metal compounds. In the preparation of the iron silicates the alkali metal compound is preferably a sodium compound. The alkali metal ions present in the aqueous mixture from which the iron 10 silicates are prepared, find their way, at least partly, into the silicates prepared. They can be replaced with other cations such as hydrogen ions or ammonium ions by using suitable exchange methods. The iron silicates used in the catalyst mixtures preferably have an alkali metal 15 content of less than O.l^w and in particular of less than 0.05#w. If desired, a binder material such as bentonite or kaolin may be incorporated in the catalyst mixtures.

The process according to the invention can very 20 suitably be carried out by conducting the feed in upward or downward direction through a vertically mounted reactor, in which a fixed or a moving bed of the catalyst mixture concerned is present.

The process according to the invention can also 25 very suitably be used as the first step of a two-step process for the conversion of Hg/CO mixtures into hydrocarbon mixtures. In this case carbon monoxide and hydrogen present in the reaction product of the first step, if desired together with other components of this reaction product, are contacted in a second step with 5 a catalyst containing one or more metal components with catalytic activity for the conversion of an H2/C0 mixture into acyclic hydrocarbons, which metal components have been chosen from the group formed by cobalt, nickel and ruthenium, on the understanding that if the 10 feed for the second step has an H2/C0 molar ratio of less than 1.5, water is added to this feed and that in 1 the second step a bifunctional catalyst or catalyst ^combination is used, which contains, in addition to the i. . metal components with catalytic activity for the con-15 version of an H2/C0 mixture into acyclic hydrocarbons, also one or more metal components with catalytic activity for the conversion of an H20/C0 mixture into an H2/C02 mixture.

The process according to the invention can further 20 very suitably be used as the first step of a three-step process for the preparation of an aromatic hydrocarbon mixture and middle distillates from an H2/CO mixture. In this case carbon monoxide and hydrogen present in the reaction product of the first step, if desired together 25 with other components of this reaction product, are contacted in a second step with a catalyst that contains 2 3 MAY J984 198726 -40 pbw cobalt and 0.25-5 pbw zirconium, titanium or chromium per 100 pbw silica and which has been prepared by impregnating a silica carrier with one or more aqueous solutions of salts of cobalt and zirconium, titanium or 5 chromium, followed by drying the composition, calcining it at 350-700°C and reducing it at 200-350°C, on the understanding that if the feed for the second step has an H2/C0 molar ratio of less than 1.5, water is added to the feed and that the co-impregnation catalyst is used 10 in combination with a CO-shift catalyst. Of the reaction product of the second step at least that part whose initial boiling point lies above the final boiling point of the heaviest middle distillate desired as the end product, is subjected in a third step to a catalytic 15 hydrotreatment.

The invention will now be explained with reference to the following Example.

EXAMPLE Four crystalline silicates (silicates 1-4) were 20 prepared as follows: Silicate 1 A mixture of NaOH, (C-jH^)^NOH, amorphous silica, Fe(NO^)^ and water with a molar composition of 25 Si02 . 1 Na20 . 4 .5-[ (C^H^N] 20 . 0.125 . 450 H20 was heated for 24 hours at 150°C in an autoclave under autogenous pressure. 12 ,198726 Silicate 2 A mixture of NaOH, (C^H^J^NOH, amorphous silica, NaA102 and water with a molar composition of 25 Si02 . 1 Na20 . 4 .5[ (C^^N^O . 0.18 AlgO^ . 450 HgO 5 was heated for 24 hours at 150°C in an autoclave under autogenous pressure.

Silicate 3 A mixture of NaOH, (C^H^)^NOH, amorphous silica, Pe(NO^)^ and water with a molar composition of 10 25 Si02 . 1.5 Na20 . 1.5C ()^N] 20 . 0.33 .450 H20 was heated for 48 hours at 150°C in an autoclave under autogenous pressure.

Silicate 4 A mixture of NaOH, (C^H^)^NOH, amorphous silica, 15 amorphous alumina and water with a molar composition of 25 Si02 . 1.5 Na20 . 1.5[ (C^)^N]20 . 0.33 A1203 . 450 H20 was heated for 48 hours at 150°C in an autoclave under autogenous pressure.

After the reaction mixture had cooled down the 20 silicates formed were filtered off, washed with water until the pH of the wash water was about 8, dried at 120°C and calcined at 500°C. Silicates 1-4 had the following properties: (a) thermally stable up to a temperature above 800°C, 25 (b) an X-ray powder diffraction pattern for silicates 1 and 2 as mentioned in Table A and for silicates 3 and 4 as mentioned in Table B. 198726 13 (c) an Si0„/Ao0, molar ratio as follows: silicate 1 Si02/Pe20^ molar ratio 130 " 2 Si02/Al203 " » 90 " 3 Si02/Pe203 " " 70 "4 Si02/Al203 " " 61 Silicates 5-8 were prepared from silicates 1-4, respectively by boiling silicates 1-4 with 1.0 molar NH^N03 solution, washing with water, boiling again with 1.0 molar NH|jN03 solution and washing, drying at 120°C 10 and calcining at 500°C. Subsequently, four catalyst mixtures (catalyst mixtures A-D) were prepared by mixing a Zn0-Cr203 composition with each of the silicates 5-8. The atomic Zn percentage of the Zn0-Cr203 composition, based on the sum of Zn and Cr, was 70%. The catalyst 15 mixtures all contained per part by weight silicate, 10 pbw of the Zn0-Cr203 composition.

Catalyst mixtures A-D were tested for the preparation of an aromatic hydrocarbon mixture from an H2/C0 mixture. The test was carried out in a 50-ml reactor 20 containing a fixed catalyst bed having a volume of 7.5 ml. In four experiments an H2/C0 mixture with an H2/C0 molar ratio of 0.5 was conducted over each of the catalyst mixtures A-D at a temperature of 375°C, a — 1 —1 pressure of 60 bar and a space velocity of 1000 Nl.l .h 25 In all the experiments the aromatics content of the C^+ fraction, averaged over 100 hours, was more than 40%w. 14 The other results of the experiments are listed Table C.

TABLE C Exper- Cat. Silicate Conversion of the iment mixture synthesis gas, No. No. No. %v after after 10h(C10) lOOh(CDO) 1 2 3 4 A B C D 6 7 8 58 68 60 65 52 64 58 52 Stability expressed as difference between CIO and C100 Cr- select-5 ivity averaged over 100 hours, Durene content in C5+ product averaged over 100 hours, 6 4 2 13 80 62 78 72 12.4 14.6 .4 .5 VJ1 vO 09 VJ N> 16 198726 Of the experiments listed in Table C only experiment 3, in which a catalyst mixture was. used containing an iron silicate with an X-ray powder diffraction pattern according to Table B, is an ex-5 periment according to the invention. The other experiments, in which catalyst mixtures were used containing an aluminium silicate or an iron silicate with an X-ray powder diffraction pattern according to Table A, are outside the scope of the invention. They 10 have been included in the patent application for comparison. The results of experiments 1 and 2 (both carried out using a silicate with an X-ray powder diffraction pattern according to Table A) show the higher C^+ selectivity obtained when an iron silicate is used 15 in comparison with an aluminium silicate.

The results of the experiments 1 and 3 (both carried out using an iron silicate) show the higher stability and the lower durene production obtained when an iron silicate is used with an X-ray powder dif-20 fraction pattern according to Table B in comparison with an iron silicate with an X-ray powder diffraction pattern according to Table A. 17

Claims (12)

WHAT WE CLAIM IS:

1. A process for the preparation of an aromatic hydrocarbon mixture, characterized in that an Hg/CO mixture is contacted, at a temperature of 200 - 500°C, a pressure of 1 - 150 bar and a space velocity of 50 - 5000 N1 gas/1 catalyst/h, with a mixture of two catalysts of which one has the capability of catalyzing the oonversion of an H2/C0 mixture into acyclic oxygen-containing hydrocarbons and the other is a crystalline iron silicate which has, after one hour's calcining in air at 500°C, the following properties: (a) thermally stable up to a temperature above 600°C, (b) an X-ray powder diffraction pattern showing the reflections given in Table B (below), and (c) in the formula which gives the composition of the silicate, expressed in moles of the oxides, the SiC^/FegO^ molar ratio is more than 10, -18- 198726 18 TABLE B d(£) Relative intensity d(8) Relative intensity 11.1 100 3.84 65 10.0 70 3-70 20 7.42 2 3.63 < 2 6.68 5 3.47 2 6.35 2 3.34 1 5.97 16 3-30 4 5.70 < 1 3-05 5 5.56 8 2.98 9 4.98 6 2.86 1 4.60 3 2.60 2 4.35 5 2.48 * 3 4.25 < 1 2.40 2 4.00 < 1

2. A process according to claim 1, characterized in that the molar ratio of hydrogen to carbon monoxide in the feed lies between 0.25 and 1.0.

3. A process according to claim 1 or 2, characterized in that it is carried out at a temperature of 300-450°C, a pressure of 5-100 bar and a space velocity of 300-3000 N1 gas/1 catalyst/h. 19 198726

4. A process according to any one of claims 1-3, characterized in that the catalyst mixture has been built up of a catalyst X and a catalyst Y, catalyst X being capable of converting an f^/CO mixture into 5 substantially methanol and/or dimethyl ether and catalyst Y being the crystalline iron silicate.

5. A process according to claim 4, characterized in that as X-catalyst a composition is used which contains zinc together with chromium. 10

6. A process according to claim 5, characterized in that in the catalyst X the atomic percentage of zinc, based on the sum of zinc and chromium, is 60-80%.

7. A process according to any one of claims 4-6, characterized in that the catalyst mixture contains 15 per part by volume of catalyst Y 1-5 parts by volume of catalyst X.

8. A process according to any one of claims 1-7, characterized in that the catalyst mixture contains a crystalline silicate with an alkali metal content 20 of less than 0.05$w.

9. A process according to any one of claims 1-8, characterized in that it is used as the first step of a two-step process for the conversion of E^/CO mixtures into hydrocarbon mixtures, in which carbon monoxide and 25 hydrogen present in the reaction product of the first step, if desired together with other components of this ■ ■ 20 reaction product, are contacted in a second step with a catalyst containing one or more metal components with catalytic activity for the conversion of an ^/CO mixture into acyclic hydrocarbons, which metal com-5 ponents have been selected from the group formed by cobalt, nickel and ruthenium, on the understanding that if the feed for the second step has an I^/CO molar ratio of less than 1.5, water is added to this feed and that in the second step a bifunctional catalyst or catalyst 10 combination is used, which, in addition to the metal components with catalytic activity for the conversion of an I^/CO mixture into acyclic hydrocarbons, also contains one or more metal components with catalytic activity for the conversion of an I^O/CO mixture into 15 an H2/CO2 mixture.

10. A process according to any one of claims 1-8, characterized in that it is used as the first step of a three-step process for the preparation of an aromatic hydrocarbon mixture and middle distillates from an H^/CO mixture, in 20 which carbon monoxide and hydrogen present in the reaction product of the first step, if desired together with other components of this reaction product are contacted in a second step with a catalyst that contains 10-40 pbw cobalt and 0.25-5 pbw zirconium, titanium or 25 chromium per 100 pbw silica and which has been prepared by impregnating a silica carrier with one or more aqueous solutions of salts of cobalt andx^^^^Uum, titanium r 0> *' -6JUf\i!984r ' ** ^ 21 or chromium, followed by drying the composition, calcining it at 350-700°C and reducing it at 200-350°C, on the understanding that if the feed, for the second step has an K^/CO molar ratio of less than 1.5, water 5 is added to the feed, and that the co-impregnation catalyst is used in combination with a CO-shift catalyst, and in which of the reaction product of the second step at least that part whose initial boiling point lies above the final boiling point of the heaviest middle 10 distillate desired as the end product, is subjected in a third step to a catalyst hydrotreatment.

11. A process for the preparation of hydrocarbon mixtures, substantially as described hereinbefore with reference to experiment 3 of the Example. ■ 15

12. Hydrocarbon mixtures prepared using a process according to claim 11. 0ATED THIS <3^ DAY OF ^ 195^ A. J. PARK & SON per cv AGENTS FOR THE APPLICANTS