GB2073237A - Process for the Preparation of Hydrocarbons and Hydrocarbons so Prepared - Google Patents

Abstract

Two-stage process for the preparation of hydrocarbons from syngas with an H2/CO mol. ratio between 1.0 and 2.0, in which the syngas is contacted in a first stage with a bi- or trifunctional catalyst comprising a crystalline silicate with ZSM-5 structure followed by contacting at least the C<{>2 fraction of the first stage product in a second stage with a mono- or bifunctional catalyst comprising a Ni, Co or Ru Fischer-Tropsch function. In this way an economical very attractive process combination is achieved for the production of both aromatics and paraffins.

Description

SPECIFICATION Process for the Preparation of Hydrocarbons and Hydrocarbons so Prepared The invention relates to a process for the preparation of a hydrocarbon mixture from a mixture of carbon monoxide and hydrogen with an H2/CO molar ratio of less than 2.0, using a bifunctional catalyst combination (I) containing one or more metal components with catalytic activity for the conversion of an H2/CO mixture into acyclic hydrocarbons and/or acyclic oxygen-containing hydrocarbons and a crystalline silicate having the capability of catalyzing the conversion of acyclic hydrocarbons and acyclic oxygen-containing hydrocarbons into aromatic hydrocarbons, on the understanding that if the H2/CO mixture has an H2/CO molar ratio below 1.5, use is made of a trifunctional catalyst combination containing one or more metal components with catalytic activity for the conversion of an H2/CO mixture into acyclic hydrocarbons and/or acyclic oxygen-containing hydrocarbons, one or more metal components with catalytic activity for the conversion of an H2/CO mixture into an H2/CO2 mixture and a crystalline silicate having the capability of catalyzing the conversion of acyclic hydrocarbons and acyclic oxygen-containing hydrocarbons into aromatic hydrocarbons.Said crystalline silicates are characterized in that they have the following properties after one hour's calcination in air at 5000C: a) an X-ray powder diffraction pattern showing as strongest lines the 4 lines stated in Table A: Table A d(A) Relative intensity 11.1+0.2 VS 10.0+0.2 VS 3.84+0.07 S 3.72+0.06 S wherein the letters used have the following meaning:VS=very strong; S=strong, and b) in the formula which represents the composition of the silicate, expressed in moles of the oxides, and in which, in addition to oxides of hydrogen, alkali metal and/or alkaline-earth metal and silicon, there is present one or more oxides of a trivalent metal A selected from the group formed by aluminium, iron, gallium, rhodium, chromium and scandium, the Al203/SiO2 molar ratio (for the sake of brevity further designated m in this patent application) is less than 0.1.

In an investigation by the Applicant concerning this process it was found that it has two drawbacks. In the first place, when using space velocities acceptable in actuai practice, the conversion of the HdCO mixture is found to be unsatisfactory. Further, the process yields a product substantially consisting of hydrocarbons with at most 12 carbon atoms in the molecule and only very few hydrocarbons with more than 12 carbon atoms in the molecule.

Further investigation by the Applicant concerning this process has shown that the two abovementioned drawbacks can be obviated by giving the reaction product, or at least its C2 fraction, an after-treatment by contacting it with a catalyst containing one or more metal components with catalytic activity for the conversion of an H2/CO mixture into acyclic hydrocarbons, which metal components have been selected from the group formed by Ni, Co and Ru, on the understanding that if the feed for the second step has an H2/CO molar ratio of less than 1.5, water is added to this feed and that in the second step a bifunctional catalyst combination (II) is used; which contains, in addition to metal components with catalytic activity for the conversion of an H2/CO mixture into acyclic hydrocarbons, also one or more metal components with catalytic activity for the conversion of an H20/CO mixture into an HICK2 mixture. In this way it is achieved that when using space velocities acceptable in actual practice, not only a very high conversion of the H2/CO mixture is obtained, but also that the reaction product consists substantially of hydrocarbons with more than 1 2 carbon atoms in the molecule.

The present invention therefore relates to a process for the preparation of a hydrocarbon mixture, in which a mixture of carbon monoxide and hydrogen with an H2/CO molar ratio of less than 2.0 is contacted in a first step with a bifunctional catalyst combination (I) as defined above, on the understanding that if the HiCO mixture has an H2/CO molar ratio of less than 1.5, a trifunctional catalyst combination as defined above is used, at least the C2- fraction of the reaction product from the first step being contacted in a second step with a monofunctional catalyst as defined above, on the understanding that, if the feed for the second step has an H2/CO molar ratio of less than 1.5, water is added to this feed and that in the second step a bifunctional catalyst combination (II) as defined above is used.

The Netherlands patent application No. 7906003 filed on 6th August, 1979, relates to a process for the preparation of a hydrocarbon mixture, in which a mixture of carbon monoxide and hydrogen with an H2/CO molar ratio of less than 1.0 is contacted in a first step with a trifunctional catalyst combination as defined above and in which at least the C2- fraction of the reaction product from the first step is contacted in a second step with a monofunctional catalyst as defined above, on the understanding that, if the feed for the second step has an H2/Co molar ratio of less than 1.5, water is added to this feed and that in the second step a bifunctional catalyst combination (II) as defined above is used.

The present patent application therefore relates to a process for the preparation of a hydrocarbon mixture, in which a mixture of carbon monoxide and hydrogen with an H2/CO molar ratio of 1.0-2.0 is contacted in a first step with a bifunctional catalyst combination (I) as defined above, on the understanding that, if the HCO mixture has an H2/CO molar ratio of less than 1.5, a trifunctional catalyst combination as defined above is used, and in which at least the C2-fraction of the reaction product from the first step is contacted in a second step with a monofunctional catalyst as defined above, on the understanding that, if the feed for the second step has an H2/CO molar ratio of less than 1.5, water is added to this feed and that in the second step a bifunctional catalyst combination (II) as defined above is used.

In the process according to the invention the starting material is an H2/CO mixture with an HJCO molar ratio of less than 2.0. Such H2/CO mixtures can very suitably be prepared by steam gasification of a carbon-containing material. Examples of such materials are brown coal, anthracite, coke, crude mineral oil and fractions thereof and oils extracted from tar sand and bituminous shale. The steam gasification is preferably carried out at a temperature of 900-1 5000C and a pressure of 1 0-100 bar. In the process according to the invention it is preferred to start from an H2/CO mixture with an H2/CO molar ratio of more than 0.25.

The bi- and trifunctional catalyst combinations used in the process according to the invention in the first step contain, in addition to the metal components with catalytic activity, a crystalline metal silicate characterized by the properties mentioned under (a)-(c). Aithough, in principle the silicates may contain several metals selected from the group formed by aluminium, iron, gallium, rhodium, chromium and scandium, it is preferred for the process according to the invention to use catalysts in which the silicate contains only one of these metals and in particular silicates which contain as the metal aluminium, iron or gallium. As regards the presence of aluminium in the silicates, the following remarks should be made.The silicon compounds, which from an economic point of view are suitable for the preparation of crystalline silicates on a technical scale, contain as a rule a small amount of aluminium as contaminant.

Usually, this aluminium is found, at least partly, in the silicate prepared. This means that, if the aim is to prepare for use in the bi and trifunctional catalyst combinations a crystalline silicate containing one or more of the metals iron, gallium, rhodium, chromium and scandium, whilst the starting material is a base mixture in which a silicon compound contaminated with aluminium has been incorporated, as a rule a crystalline silicate will be obtained containing a slight amount of aluminium.

The crystalline silicates used in the bi- and trifunctional catalyst combinations should have a value for m which is less than 0.1. It is preferred to use crystalline silicates for which m is greater than 0.001 and in particular greater than 0.002 and silicates for which m is smaller than 0.05. if in the process according to the invention use is made of a bi- or trifunctional catalyst combination in which a crystalline aluminium silicate is present for which m is greater than 0.005, it is preferred to choose for this purpose an aluminium silicate which contains 0.110% w of one of the elements selected from the group formed by manganese, calcium, magnesium and titanium, in particular manganese.

The crystalline silicate used in the bi- and trifunctional catalyst comhinations has been defined, inter alia, with reference to the X-ray powder diffraction pattern. This X-ray powder diffraction pattern should contain, as strongest lines, the four lines shown in Table A. The complete X-ray powder diffraction pattern of a typical example of a silicate suitable for use according to the invention is shown in Table B:: Table B d( ) Relative intensity d(A) Relative intensity 11.1 100 4.00 3 10.0 70 3.84 57 8.93 1 3.72 31 7.99 1 3.64 10 7.42 1 3.44 5 6.68 7 3.34 3 6.35 11 3.30 5 5.97 18 3.25 2 5.70 7 3.05 5 5.56 10 2.98 12 5.35 2 2.96 3 4.98 6 2.86 2 4.60 4 2.73 2 4.35 5 2.60 2 4.25 7 2.48 3 4.07 2 2.40 2 The crystalline silicates used in the bi and trifunctional catalyst combinations can be prepared starting from an aqueous mixture containing the following compounds: one or more compounds of an alkali metal or alkaline-earth metal (M), one or more compounds containing an organic cation (R) or from which such a cation is formed during the preparation of the silicate, one or more silicon compounds and one or more compounds in which a trivalent metal A selected from the group formed by aluminium, iron, gallium, rhodium, chromium and scandium is present. The preparation is performed by maintaining the mixture at elevated temperature until the silicate has been formed and subsequently separating the crystal of the silicate from the mother liquor and calcining them.In the aqueous mixture from which the silicates are prepared the various compounds should be present in the following ratio, expressed in moles of the oxides: M210 :R20=0.1-20, R20:SiO2=O.O 1-0.5, Si02:Al203 > 1 0, and H20:Si02=5-50; (n is the valency of M) In the preparation of the silicates it is preferred to start from a base mixture in which M is present in an alkali metal compound and R in a tetra-alkylammonium compound and in particularfrom a base mixture in which M is present in a sodium compound and R in a tetrapropylammonium compound. The crystalline silicates prepared as described above contain alkali metal ions and/or alkaline-earth metal ions. They can be replaced by other cations such as hydrogen ions or ammonium ions by using suitable exchange methods.The crystalline silicates used in the bi- and trifunctional catalyst combinations preferably have an alkali metal content of less than 0.1% wand in particular less than 0.05 % w.

Although the trifunctional catalyst combinations are described in this patent application as catalyst combinations containing one or more metal components with catalytic activity for the conversion of an H2/CO mixture into acyclic hydrocarbons and/or acyclic oxygen-containing hydrocarbons and one or more metal components with catalytic activity for the conversion of an H20/CO mixture into an H2/CO2 mixture, this does not mean at all that separate metal components that each have one of the two catalytic functions should always be present in the trifunctional catalyst combinations.For, it has been found that metal components and combinations of metal components with catalytic activity for the conversion of an H2/CO mixture into substantially acyclic oxygencontaining hydrocarbons often also have sufficient catalytic activity for the conversion of an H20/CO mixture into an H2/CO2 mixture, so that incorporation of one metal component or one combination of metal components into the trifunctional catalyst combinations will then usually suffice. Metal components and combinations of metal components with catalytic activity for the conversion of an H2/CO mixture into substantially acyclic hydrocarbons, usually have no or insufficient activity for the conversion of an 1^120/CO mixture into an H2/CO2 mixture.When using such metal components or combinations of metal components in the trifunctional catalyst combinations, one or more separate metal components with catalytic activity for the conversion of an H20/CO mixture into an H2/CO2 mixture should therefore in most cases be incorporated into these metal components.

The bi- and trifunctional catalyst combinations used in the first step of the process according to the invention are preferably composed of two or three separate catalysts, which will, for convenience, be designated catalysts X, Y and Z. Catalyst X is the one containing the metal components having catalytic activity for the conversion of an H2/CO mixture into acyclic hydrocarbons and/or acyclic oxygen-containing hydrocarbons. Catalyst Y is the crystalline silicate. Catalyst Z is the one containing the metal components having catalytic activity for the conversion of an H20/CO mixture into an H2/CO2 mixture. As has been explained hereinbefore the use of a Z-catalyst may in some cases be omitted for the trifunctional catalyst combinations.

If as the X-catalyst a catalyst is used which is capable of converting an H2/CO mixture into substantially acyclic oxygen-containing hydrocarbons, preference is given to a catalyst which is capable of converting an HCO mixture into substantially methanol and/or dimethyl ether. Very suitable catalysts for this purpose are ZnO-Cr203 compositions, in particular such compositions in which the atomic percentage of zinc, based on the sum of zinc and chromium, is at least 60%80%.

When using a Zn0-Cr203 composition as X-catalyst, the use of a Z-catalyst may be omitted for the trifunctional catalyst combinations.

X-catalysts which are capable of converting an H2/CO mixture into substantially acyclic hydrocarbons are referred to in the literature as Fischer-Tropsch catalysts. Such catalysts contain one or more metals from 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. If in the first step of the process according to the invention use is made of a bi- or trifunctional catalyst combination in which the X-catalyst is a Fischer-Tropsch cataiyst, it is preferred to choose for this purpose an iron or cobalt catalyst, in particular such a catalyst which has been prepared by impregnation.Very suitable catalysts for this purpose are: (a) Catalysts that contain 30-75 pbw iron and 5-40 pbw magnesium for 100 pbw alumina and which have been prepared by impregnating an alumina carrier with one or more aqueous solutions of salts of iron and of magnesium followed by drying the composition, calcining it at a temperature of 700-1 2000C and reducing it. Particular preference is given to such catalysts that contain, in addition to 40-60 pbw iron and 7.5-30 pbw magnesium, 0.5-5 pbw copper as the reduction promoter and 1-5 pbw potassium as the selectivity promoter per 100 pbw alumina, and which have been calcined at 750-8500C and reduced at 2500--3500C.

(b) Catalysts that contain 10-40 pbw iron and 0.25-10 pbw chromium per 100 pbw silica and which have been prepared by impregnating a silica carrier with one or more aqueous solutions of salts of iron and of chromium, followed by drying the composition, calcining it and reducing it at a temperature of350-7500C. Particular preference is given to such catalysts which contain, in addition to 20-35 pbw iron and 0.5-5 pbw chromium, 1-5 pbw potassium as the selectivity promoter and which have been calcined at 350-7000C and reduced at 350-5000C.

(c) Catalysts that contain 10 40 pbw cobalt and 0.25-5 pbw zirconium, titanium or chromium per 100 pbw silica and which have been prepared by impregnating a silica carrier with one or more aqueous solutions of salts of cobalt and zirconium, titanium or chromium followed by drying the composition, calcining it at 350-7000C and reducing it at 200-3500C.

When using the iron catalysts mentioned under (a) and (b) as X-catalyst, the use of a Z-catalyst can be omitted. When using the cobalt catalysts mentioned under (c) as X-catalyst, a Z-catalyst should also be incorporated into the trifunctional catalyst combinations. If in the first step of the process according to the invention use is made of a bi- or trifunctional catalyst combination in which catalyst X is a Fischer-Tropsch catalyst, it is preferred to choose for this purpose an iron catalyst as described under (a) and (b).

Z-catalysts which are capable of converting an H2O/CO mixture into HCO2 mixture are referred to in the literature as CO-shift catalysts.

In the bi- and trifunctional catalyst combinations the catalysts X, Y and, optionally, Z are preferably present as a physical mixture. When carrying out the first step of the process, using a fixed catalyst bed, this bed may also be built up of alternate layers of particles of the catalysts X, Y and, optionally Z.

The first step of the process according to the invention can very suitably be carried out by conducting the feed in upward or in downward direction through a vertically mounted reactor in which a fixed or moving bed of the bi- or trifunctional catalyst combination is present. The first step may, for instance, be carried out in the so-called fixed-bed operation, in bunker-flow operation, in ebullated-bed operation or fluidized-bed operation.The first step of the process is preferably carried out under the following conditions: a temperature of 200-5000C and in particular 250-4500C, a pressure of 1 - 1 50 bar and in particular of 5-100 bar and a space velocity of 50-5000 and in particular of 3003000 N1 gas/I catalyst/h.

In the process according to the invention at least the C2- fraction of the reaction product from the first step is used as the feed for the second step. Instead of the C2 fraction of the reaction product from the first step, a different fraction of this product, e.g. the C4- fraction, or even the whole product from the first step, may be used-if desired-as the feed for the second step.In the second step of the process according to the invention it is intended to convert as much as possible of the CO present in the feed for the second step into acyclic hydrocarbons over a monofunctional catalyst containing one or more metal components with catalytic activity for the conversion of an H2/CO mixture into acyclic hydrocarbons, which metal components have been selected from the group formed by cobalt, nickel and ruthenium. To this end the HCO molar ratio in the feed for the second step should be at least 1.5 and preferably 1.75-2.25. When using an H2/CO mixture with a high H2/CO molar ratio as the feed for the first step, the process according to the invention can yield a reaction product from the first step, which has an H2/CO molar ratio of at least 1.5, which is suitable, as such, to be converted in the second step over the said catalyst.An attractive way of ensuring in the process according to the invention that the reaction product from the first step has an H2/CO molar ratio of at least 1.5 is adding water to the feed for the first step and the use of a trifunctional catalyst combination in the first step. Under the influence of the catalyst combination present in the first step this water reacts with CO from the feed to form an H2/CO2 mixture. A further advantage of the addition of water to the feed of the first step in the process according to the invention is that it increases the stability of the trifunctional catalyst combination.Water addition to the feed for the first step, and a trifunctional catalyst combination can be applied in the process according to the invention both in cases where without water addition the first step would have given a reaction product with an HiCO molar ratio of less than 1.5, and in cases where, also without water addition, the first step would have given a reaction product with an H2/CO molar ratio of at least 1.5, but where it is desirable that the feed which is contacted with the catalyst in the second step has a higher HCO molar ratio. If in the process according to the invention an embodiment is chosen in which water is added to the feed for the first step, and a trifunctional catalyst combination is used, the amount of water required is substantially determined by the HCO molar ratio of the feed for the first step, the activity of the trifunctional catalyst combination in the first step for converting an H2O/CO mixture into an H2/CO2 mixture and the desired H2/CO molar ratio of the reaction product of the first step.

If in the process according to the invention a reaction product is obtained from the first step with an HCO molar ratio of less than 1.5, after water addition to the feed for the first step or not and using a trifunctional catalyst combination, water should be added to the feed for the second step and in the second step a bifunctional catalyst combination (II) should be incorporated, which contains, in addition to the metal component with catalytic activity for the conversion of an H2/CO mixture into acyclic hydrocarbons, also one or more metal components with catalytic activity for the conversion of an H2O/CO mixture into an H2/CO2 mixture.The bifunctional catalyst combinations which are optionally used in the second step of the process according to the invention, are preferably composed of two separate catalysts, which will, for convenience, be designated catalyst A and catalyst B. Catalyst A is the one containing the metal components having catalytic activity for the conversion of an Hz/CO mixture into acyclic hydrocarbons, and which metal components have been selected from the group formed by cobalt, nickel and ruthenium. Catalyst B is the one containing the metal components having catalytic activity for the conversion of an H2O/CO mixture into an H2/CO2 mixture.Both when using a monofunctional catalyst and when using a bifunctional catalyst combination in the second step of the process according to the invention, preference is given to a cobalt catalyst as the A-catalyst and in particular to a cobalt catalyst prepared by impregnation. Very suitable catalysts for this purpose are the cobalt catalysts described hereinbefore under (c). Suitable B-catalysts are the usual CO-shift catalysts.

In the bifunctional catalyst combinations (II) catalysts A and B may be present as a physical mixture.

When the second step of the process is carried out using a fixed catalyst bed, this bed is preferably built up of two or more alternate layers of particles of, successively, catalyst B and catalyst A. Water addition to the feed for the second step together with the use of a bifunctional catalyst combination in the second step can be used in the process according to the invention both in cases where the reaction product from the first step has an H2/CO molar ratio of less than 1.5, and in cases where the reaction product from the first step already has an H2/CO molar ratio of at least 1.5, but where it is desirable that the feed which is contacted with catalyst A in the second step should have a higher HiCO molar ratio.If in the process according to the invention an embodiment is chosen in which water is added to the feed for the second step together with the use of a bifunctional catalyst combination in the second step, the amount of water required is substantially determined by the H2/CO molar ratio of the feed for the second step, the activity of the catalyst combination for the conversion of an H2O/CO mixture into an H2/CO2 mixture and the desired H2/CO molar ratio of the product that is contacted with catalyst A.

The second step of the process according to the invention can very conveniently be carried out by conducting the feed in upward or in downward direction through a vertically mounted reactor in which a fixed bed of the monofunctional catalyst or of the bifunctional catalyst combination is present. The second step of the process can also be carried out using a suspension of the catalyst or catalyst combination in a hydrocarbon oil. The second step of the process is preferably carried out under the following conditions: a temperature of 1 25-3500C and in particular of 1 75-2750C and a pressure of 1-150 bar and in particular of 5-100 bar.

The invention will now be explained with reference to the following example: Example The following catalysts were used in the investigation: Catalyst 1 A Co/Zr/SiO2 catalyst that contained 25 pbw cobalt and 1.8 pbw zirconium per 100 pbw silica and which had been prepared by impregnating a silica carrier with an aqueous solution containing a cobalt and a zirconium salt, followed by drying the composition, calcining it at 5000C and reducing it at 2800C.

Catalyst 2 An Fe/Mg/Cu/K/Al2O3 catalyst that contained 50 pbw iron, 20 pbw magnesium, 2.5 pbw copper and 4 pbw potassium per 100 pbw alumina and which had been prepared by impregnating an alumina carrier with an aqueous solution containing an iron, a magnesium, a copper and a potassium salt, followed by drying the composition, calcining it at 8000C and reducing it at 3250C.

Catalyst 3 An Fe/Cu/K/SiO2 catalyst that contained 25 pbw iron, 1.25 pbw copper and 2 pbw potassium per 100 pbw silica and which had been prepared by impregnating a silica carrier with an aqueous solution containing an iron, a copper and a potassium salt, followed by drying the composition, calcining it at 400"C and reducing it at 2800 C.

Catalyst 4 A Cu/Zn/Al2O3 catalyst with a Cu/Zn atomic ratio of 0.55.

Catalyst 5 A ZnO-Cr2O3 catalyst in which the atomic percentage of zinc based on the sum of zinc and chromium was 70%.

Catalysts 6-8 Three crystalline silicates (silicates A-C) were prepared by heating mixtures of SiO2, NaOH, [(C3H7)4N]OH and ether NaAlO2, or Fe(NO3)3, or Ga(NO3)3 in water for six hours at 150 C in an autoclave under autogenous pressure. After the reaction mixtures had cooled down, the silicates formed were filtered off, washed with water until the pH of the wash water was about 8, dried at 1 200C and calcined at 5000C.

The silicates A-C had the following properties: (a) thermally stable up to a temperature above 8000C, (b) an X-ray powder diffraction pattern substantially equal to the one given in Table B, (c) a value for m as mentioned below: silicate A:Al2O3/SiO2 molar ratio=0.0133, silicate B:Fe2O3/SiO2 molar ratio=0.0050, silicate C:Ga2O3/SiO2 molar ratio=0.0083.

The molar composition of the aqueous mixtures from which the silicates A-C were prepared can be represented as follows: Silicate A: 1 Na2O . 4.5kC7)4N]20 .0.33 Al203.25 SiO2 . 450 H20 Silicate B: 1 Na2O . 1.5[(C3H7)4N]2O . 0.125 Fe2O3 . 25 SiO2 . 468 H2O Silicate C: 1 Na2O . 4.5[(C3H7)4N]2O. 0.22 Ga203.25 SiO2 . 450 H20.

The silicates D-F were prepared from the silicates A-C, respectively, by boiling the silicates A-C with 1.0 molar NH4NO3solution, washing with water, boiling again with 1.0 molar NH4NO3 solution and washing, drying and calcining. A catalyst 6 was prepared from silicate D by impregnating silicate D with an aqueous solution of a manganese salt followed by drying the composition and calcining it. Catalyst 6 contained 3% w manganese.

Silicates E and F were used as such as catalyst 7 and catalyst 8, respectively.

Catalyst Mixtures I-Vl Six catalyst mixtures were prepared. The catalyst mixtures I V consisted each of a physical mixture of two of the above-mentioned catalysts in the following ratio: Cat. mixture I=2 pbv of cat 5+1 pbv of cat. 6, Cat. mixture II=2 pbv of cat 5+1 pbv of cat. 7, Cat. mixture III=2 pbv of cat 5+1 pbv of cat. 8, Cat. mixture IV=2.5 pbv of cat. 2+1 pbv of cat. 6, Cat. mixture V=2 pbv of cat 3+1 pbv of cat 7.

Catalyst mixture VI consisted of a layer of catalyst 4 and a layer of catalyst 1 in a volume ratio of 1:2.

The catalyst mixtures I-VI and catalyst 1 were tested for the preparation in one or two steps of a hydrocarbon mixture from an H2/CO mixture. The test was carried out in one or two reactors of 50 ml each, in which a fixed catalyst bed was present. Twenty-three experiments were carried out. The experiments 1, 4, 7, 10, 15, 17, 19 and 22 were carried out in one step; the other experiments in two steps. In all the experiments, with the exception of experiments 14 ,22 and 23, a te,perature of 3750C was used in the first step. In experiment 14 the temperature in the first step was 2800C and in the experiments 22 and 23 the temperature in the first step was 2500C.

In all the experiments carried out in two steps the temperature in the second step was 2200C. In all the experiments, with the exception of experiments 1 4, 22 and 23, a pressure of 60 bar was used.

In experiments 14, 22 and 23 the pressure was 30 bar. In the experiments 1, 4, 7 and 10 the space velocity was 1000 N1.1-1.h-1. In the experiments 15, 17, 19 and 22 the space velocity was 500 N1.1-1.h-1. In all the experiments carried out in two steps the space velocity, based on the sum of the total catalyst system (in the first and second step) was 500 N1.1-1.h-1. In the experiments 6, 9, and 12 the C4-fraction of the product from the first was used as the feed for the second step. In the remaining experiments which were carried out in two steps, the total reaction product from the first step was used as the feed for the second step. The results of the experiments are stated in Table C. Table C Experiment No. 1 2 3 4 5 6 7 8 9 10 11 12 Cat. mixture in the first I I I I I I II II II III III III step, No.

Quantity of catalyst in the 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 first step, ml H2/CO ratio of the feed for 0.8 0.8 0.8 0.45 0.45 0.45 0.45 0.45 0.45 0.45 0.45 the first step Amount of water added to the - - - 115 52 115 115 52 115 115 52 115 feed for the first step, ml. ml-1 . h-1 H2/CO ratio of the product 1.7 1.7 1.7 2.0 2.0 2.0 1.9 1.7 1.9 2.1 2.1 2.1 from the first step Cat. or cat. mixture in the - I 1 - I 1 - II 1 - III 1 second step, No.

Quantity of catalyst in the - 7.5 7.5 - 7.5 7.5 - 7.5 7.5 - 7.5 7.5 second step, ml Amount of water added to the - - - - - - - - - - - feed for the first step, ml. ml-1 . h-1 Conversion of the synthesis 62 78 94 53 68 98 49 64 97 55 69 98 gas, % Composition of the reaction product, % w C4- 40 50 45 37 47 36 29 30 35 26 36 34 C5-C12 57 47 38 58 48 31 69 68 32 70 60 33 C13-C19 3 3 7 5 5 13 2 2 13 4 4 13 C20+ - - 10 - - 20 - - 20 - - 20 Table C (cont.) Experiment No. 13 14 15 16 17 18 19 20 21 22 23 Cat. mixture in the mixture I IV I I II II II II II V V step, No.

Quantity of catalyst in the 7.5 7.5 15 3.75 15 3.75 15 2.5 2.5 15 5 first step, ml H2/CO ratio of the feed for 0.45 0.9 1.3 1.3 1.3 1.3 1.1 1.1 1.1 1.57 1.57 the first step Amount of water added to the 15 - - - - - - - 29 - feed for the first step, ml . ml-1 . h-1 H2/CO ratio of the product 0.5 1.8 17 2.0 17 2.0 31 1.43 2.0 1.87 1.7 from the first step Cat. or cat. mixture in the VI 1 - 1 - 1 - VI 1 - 1 second step, No.

Quantity of catalyst in the 7.5 7.5 - 11.25 - 11.25 - 12.5 12.5 - 10 second step, ml Amount of water added to the 100 - - - - - - 29 - - feed for the second step, ml . ml-1 . h-1 Conversion of the synthesis 98 95 62 97 62 97 70 96 96 60 94 gas % Composition of the reaction product % w C4- 29 50 40 18 25 21 25 13 10 45 24 C5-C12 49 35 57 43 72 46 73 42 56 51 39 C13-C19 10 6 3 16 3 16 2 17 14 4 14 C20+ 12 9 - 23 - 23 - 28 20 - 23 Of the experiments listed in the table, only the two-step experiments 3, 6, 9, 12, 13, 14, 1 6, 1 8, 20, 21 and 23 are experiments according to the invention. The one-step experiments 1, 4, 7, 10, 1 5, 1 7, 19 and 22 and the two-step experiments 2, 5, 8 and 11 are outside the scope of the invention. They have been included in the patent application for comparison.Of the two-step experiments 3,6, 9, 12, 13, 14, 1 6, 1 8, 20, 21 and 23 only the experiments 16, 18, 20, 21 and 23 are experiments according to the present patent application. The two-step experiments 3, 6, 9, 12, 13 and 14 are experiments according to the Netherlands patent application No. 7906003.

The advantages of the two-step process according to the invention as regards the conversion of the H2/CO mixture and the composition of the reaction product are evident when the results of the following experiments are compared: Experiments 3 with experiments 1 and 2 6 4 4and5 9 " 7 and 8 " 12and13 ,, 10and11 16 " 15 18 " 17 20and21 ,, 19 23 " 22

Claims (1)

1. Claims

   1. A process for the preparation of a hydrocarbon mixture, characterized in that a mixture of carbon monoxide and hydrogen with an H2/CO molar ratio of 1.02.0 is contacted in a first step with a bifunctional catalyst combination containing one or more metal components with catalytic activity for the conversion of an HCO mixture into acyclic hydrocarbons and/or acyclic oxygen-containing hydrocarbons, and a crystalline silicate which has the following properties after one hour's calcination in air at 5000C: a) an X-ray powder diffraction pattern showing as strongest lines the 4 lines stated in Table A: Table A d(A) Relative intensity 11.1+0.2 VS

   10.0+0.2 VS

   3.84+0.07 S

   3.72+0.06 S wherein the letters used have the following meanings:VS=very strong; S=strong; b) in the formula which represents the composition of the silicate, expressed in moles of the oxides, and in which, in addition to oxides of hydrogen, alkali metal and/or alkaline-earth metal and silicon, there is present one or more oxides of a trivalent metal A selected from the group formed by aluminium, iron, gallium, rhodium, chromium and scandium, the Al203/SiO2 molar ratio (m) is less than 0.1, on the understanding that, if the H2/CO mixture has an H2/CO molar ratio of less than 1.5, a trifunctional catlyst combination is used containing one or more metal components with catalytic activity for the conversion of an H2/CO mixture into acyclic hydrocarbons, and/or acyclic oxygencontaining hydrocarbons, one or more metal components with catalytic activity for the conversion of an H20/CO mixture into an H2/CO2 mixture and the crystalline silicate and that at least the C2- fraction of the reaction product from the first step is contacted in a second step with a catalyst containing one or more metal components with catalytic activity for the conversion of an H2/CO mixture into acyclic hydrocarbons, which metal components 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 H2/CO molar ratio of less than 1.5, water is added to this feed and that in the second step a bifunctional catalyst combination is used, which contains, in addition to the metal components with catalytic activity for the conversion of an HgCO mixture into acyclic hdyrocarbons, also one or more metal components with catalytic activity for the conversion of an H2O/CO mixture into an H2/CO2 mixture.

   2. A process as claimed in claim 1, characterizzed in that the crystalline silicate is an aluminium, iron or gallium silicate.

   3. A process as claimed in claim 1 or 2, characterized in that the crystalline silicate has a value for m which is greater than 0.002 but smaller than 0.05.

   4. A process as claimed in claim 2 or 3, characterized in that the crystalline silicate is an aluminium silicate which has a value for m which is greater than 0.005 and in that the silicate contains 0.1-10 % w of an element selected from the group formed by manganese, calcium, magnesium and titanium.

   5. A process as claimed in any one of claims 1-4, characterized in that the crystalline silicate has an alkali metal content of less than 0.1% w.

   6. A process as claimed in any one of claims 1-5, characterized in that the first step is carried out at a temperature of 200-5000C, a pressure of 1-150 bar and a space velocity of 50-5000 N1 gas/1 catalyst/h.

   7. A process as claimed in any one of claims 1-6, characterized in that water is added to the feed for the first step and that a trifunctional catalyst combination is used in the first step.

   8. A process as claimed in any one of claims 1-7, characterized in that the second step is carried out at a temperature of 125-350 C and a pressure of 1-150 bar.

   9. A process for the preparation of a hydrocarbon mixture as claimed in claim 1, substantially as described hereinbefore with reference to experiments 16, 18, 20, 21 and 23 of the Example.

   10. Hydrocarbon mixtures prepared according to a process as claimed in any one or more of claims 1-9.