PROCESS FOR THE PREPARATION OF HYDROCARBONS

Abstract: Process for the preparation of hydrocarbons by contact­ ing a feed comprising hydrogen, carbon monoxide and steam, the quantity of steam being 10-40%v, calculated on the H₂/CO/H₂O mixture, at elevated temperature and press­ ure with a silica supported catalyst comprising 10-40 pbw cobalt and 0.1-150 pbw zirconium, titanium or chromium per 100 pbw silica which catalyst has been prepared by impre­ gnation and/or kneading.

Description: PROCESS FOR THE PREPARATION OF HYDROCARBONS The invention relates to a process for the preparation of hydrocarbons by catalytic reaction of carbon monoxide with hydrogen. The preparation of hydrocarbons from a H2/CO mixture by contacting this mixture at elevated temperature and pressure with a catalyst is known in the literature as Fischer-Tropsch hydrocarbon synthesis. Catalysts often used for this purpose contain iron or cobalt together with one or more promoters and/or a carrier material. The conventional techniques of preparing Fischer-Tropsch catalysts are the precipitation route, the melting route and the impregnation route. Of these techniques the impregnation route is much to be preferred since this route is not so costly and/or time consuming, produces better reproducible results and generally yields materials with better catalytic properties. Briefly, the impregnation route involves contacting a porous carrier in the presence of a liquid once or several times with an iron or cobalt compound and, if desired, with one or more compounds of the appropriate promoters, followed by removal of the liquid and calcination and reduction of the catposition obtained. The preparation of catalysts which, in addition to iron or cobalt, contain one or more promoters may be carried out both by impregnation and by separate impregnation. In the case of co- impregnation the porous carrier is contacted once or several times with both an iron or cobalt compound and one or more compounds of the relevant promoters. In the case of separate impregnation the porous carrier is first contacted with an iron or cobalt compound or with one or more compounds of the relevant promoters and, after calcination of the composition thus obtained, the latter is contacted with one or nDre compounds of the relevant promoters or with an iron or cobalt compound, respectively, followed by calcination and reduction of the caoposition. For preparing Fischer-Tropsch catalysts comprising cobalt supported on a carrier an attractive method was recently found which can be carried out in a simple manner and yields catalysts of very good properties. In this method the deposition of the cobalt on the carrier is carried out by kneading instead of impregnation. The catalyst preparation by kneading is similAr to the preparation by impregnation carried out by contacting a porous carrier with one or more compounds of the catalytically active metals in the presence of a liquid, followed by the removal of the liquid and calcination of the composition, but before and/or during the removal of the liquid the composition is subjected to an intensive mechanical treatment such as pressing, squeezing or wringing, which generally has as a result that a substantizl decrease of the particle size of the carrier material occurs and that the composition takes on the consistency of a paste. Generally several hours' kneading in a suitable kneading machine is sufficient to achieve the desired kzmDgeneous dispersion of the components over the mixture. The e intensive mechanical treatment in which a substantial decrease of the particle size of the carrier material occurs, forms the principle difference between the kneading route and the impregnation route. It is true that in the preparation of a catalyst by impregnation a stage may be passed in which the composition contains an amount of liquid corresponding to that present in the aboveementioned paste and that - e.g. by stirring sate mechanical energy may be supplied to the composition, but as a rule the particle size of the carrier material remains substan tally unchanged in the catalyst preparation by impregnation Hereinafter, whenever mention is made of the preparation of catalysts by kneading, this should be taken to be the abovedescribed preparation route in which at least the cobalt has been deposited on the carrier by kneading. Any promoters present on the carrier may also have been deposited on the carrier by kneading or impregnation. The composition of the product obtained in the Fischer Tropsch !hydrocarbon synthesis by using catalysts prepared by impregnation and/or kneading is largely dependent on the catalytically active metal which is present on the catalyst. The use of a cobalt catalyst prepared by impregnation and/or kneading results in a product which consists mainly of unbranched paraffins. The use of an iron catalyst prepared by impregnatian results in a product which contains a considerably quantity of olefins and oxygen-containing organic compounds. With a view to the composition of the product obtained, for the preparation of products suitable for use as motor fuels, preference is given to the use of a cobalt catalyst. Especially catalysts which, in addition to cobalt, contain silica and in which the quantity of cobalt is 10-40 pbw per 100 pbw silica, are very suitable for the present purpose. An important parameter in the preparation of hydrocarbons from H2/CO mixtures is the C3+ selectivity of the catalyst used. According as this C3 selectivity is higher, a larder percentage of the hydrocarbon mixture obtained will consist of valuable C3+ hydrocarbons and consequently a smaller percentage will consist of C2 hydrocarbns as by-products. Although the aforetentioned catalysts containing 10-40 pbw cobalt per 100 pbw silica do already have a C3 selectivity of about 80 %, the need is nevertheless felt to boost the selectivity of these catalysts and so to reduce the formation of undesirable c2 by-products. An investigation carried out into this subject revealed that the C3+ selectivity of catalysts containing 10-40 pbw cobalt per 100 pbw silica can be considerably enhanced by using a feed which contains steam, provided that the following conditions are met: a) the catalyst must contain 0.1-150 pbw of a promoter chosen fran the group formed by zirconium, titanium or chromium per 100 pbw silica, b) the cobalt and the promoter have have been deposited on the silica by impregnation and/or kneading, and c) the quantity of steam present in the feed must be 10-40 %v, calculated on the H2/CO/H2O mixture. The following may be remarked on points a)-c). EXperiments using non-pranted Co/SiO2 catalysts prepared by kneading have shown that the presence of steam in the feed has no effect on the C3+ selectivity of the catalysts. EXperiments using Co/Zr/SiO2 catalysts substantially prepared by precipitation showed that neither for these catalysts did the presence of steam in the feed have an effect on the C3 selectivity. Experiments using Co/Zr/SiO2 catalysts prepared by impregnation and/or kneading and using feeds of various steam contents showed that significant enhancement of the C3 selectivity of these catalysts can only be achieved when the quantity of steam is at least 10 and at most 40 %v, calculated on the H2/CO/H2O mixture. The use of feeds with lower or higher steam contents (e.g. 5 or 50 %v) yields an insufficient increase of the C3 selectivity. When feeds with very high steam contents (e.g. 60 %v) are used, the C3+ selectivity will be even lower than in steam-free operations. Attempts at utilizing the afore-mentioned find for raising the C3+ selectivity of the closely related iron catalysts have remained unsuccessful. Experiments using promoted Fe/SiO2 catalysts prepared by impregnation have shown that the use both of feeds with law steam contents (e.g. 5 %v) and of feeds with higher steam contents (e.g. 30 %v) results in a very severe drop of C3 selectivity. Furhare, contrary to what is seen for the ccbalt catalysts, the presence of steam in the feed has quite an adverse effect on the activity of the iron catalysts. The present patent application therefore relates to a process for the preparation of hydrocarbons by catalytic reaction of carton monoxide with hydrogen, in which a feed which contains hydrogen, carbon monoxide and steam and in which the quantity of steam present is 10-40 %v, calculated on the H2/CO/H2O mixture, is contacted at elevated temperature and pressure with a catalyst which comprises 5-40 pow cobalt and 0.1-150 pow of a promoter chosen from the group formed by zirconium, titanium or chromium per 100 pbw of silica and which has been prepared by depositing cobalt and the promoter on a silica carrier by impregnation and/or kneading and calcining and reducing the ccmposition obtained. The catalysts used in the process according to the invention may be prepared either exclusively by impregnation, or exclusively by kneading, or by a catbination of kneading and impregnation. If the preparation of the catalysts is carried out exclusively by impregnation, both co-zmpregnation and separate impregnation are eligible. With co-impregnation the silica carrier is contacted once or several times with a Co compound and a Zr, Ti or Cr compound. With separate inregnation optionally either first the Co and, after calcination of the composition, the Zr, Ti or Cr or first the Zr, Ti or Cr and, after calcination of the composi- tion, the Co may be deposited on the silica carrier. Both the deposition of the Co and the deposition of the Zr, Ti or Cr may be carried out in one or more steps. After the last impregnation step of the co-impregnation the metal-containing composition should be calcined. If the catalyst preparation is carried out by separate impregnation, the metal-cantaining composition should be calcined both after the last impregnation step in which the cobalt has been deposited on the silica and after the last impregnation step in which the promoter has been deposited on the silica. If the co-imr pregnation or the separate impregnation are carried out in more than one step, the metal-containing composition obtained is preferably calcined after each impregnation step. In the preparation of catalysts by a combination of kneading and impregnation first cobalt is deposited on the carrier by kneading, and then the promoter by impregnation. After calcination of the paste the catoosition contained is impregnated with a ccupound of the promoter and calcined again. If the preparation of the catalysts is carried cut exclusively by kneading the starting material may very suitably be a mixture which, in addition to silica, a liquid and a Co compaund, contains a Zr, Ti or Cr ccmçrund. The amount of liquid which may be used in the preparation of catalysts by iulpregnation may vary within wide limits. The im- pregnation is preferably carried out as what is called a "dry impregnation", which means that a quantity of liquid is applied, the volume of which substantially corresponds with the pore volume of the carrier. The amount of liquid which may be used in the preparation of catalysts by kneading may also vary within wide limits. Amounts of liquid which are smaller, equal to or larger than the pore volume of the carrier come into consideration, provided that during kneading such an amount of liquid is present that under the influence of the intensive mechanical treatment the carrier material, together with the metal compound, can yield a composition with the desired paste-like consistency. A possible excess of liquid may be removed from the composition by evaporation before or during kneading. Preferably the quantity of liquid used in the kneading has a volume which corresponds to 110-190 % of the pore volume of the carrier material. In the deposition of a metal by impregantion as well as in the deposition of a metal by kneading, the carrier material is first of all contacted with a compound of the metal concerned in the presence of a liquid. As metal compounds both organic.and inorganic compounds are eligible. As liquids both organic and inorganic liquids may be applied. In the catalyst preparation by impregnation as well as in the catalyst preparation by kneading preference is given to contacting the porous carrier with a solution of the metal carpound cancerned in a solvent. Examples of suitable aqueous solutions of zirconium ccamounds are solutions of zirconium nitrate or of zirconium chloride in water. Examples of suitable non-aqueous solutions cf zirconium and titanium compounds are solutions of zirconium tetrapropoxide in a mixture of benzene and prcpanol and solutions of tetraisopropyl orthotitanate in a mixture of isopropanol and acetyl acetone. For the deposition of cobalt on the carrier preference is given to the use of a solution of an inorganic cobalt compound in water. Cobalt compounds suitable for the purpose are cobalt nitrate, cobalt carbonate, cobalt chloride and cobalt sulphate. The e calcination(s) to be carried out in the present catalyst preparations is (are) preferably carried out at a temperature between 350 and 700 OC. After the last calcination the Co and Zr, Ti or Cr-containing composition should be reduced. This reduction is preferably carried out at a terature between 200 and 350 OC. The quantities of promoter present on the catalysts is than 0.1 pow per 100 pow silica. Depending on the method of preparation chosen, the catalysts may contain up to 150 pow per 100 pbw silica. If the catalyst preparation is carried out by separate impregnation in which first the promoter and then the cobalt is deposited on the silica, preference is given to the use of catalysts containing 2-100 and in particular 2-20 pow promoter per 100 pbw silica. If the catalyst preparation is carried out by co-impregnation, by separate impregnation in which first the cobalt and then the promoter is deposited on the silica, by kneading or by a combination of kneading and impregnation, preference is given to catalysts containing 0.1-5 pow and in particular 0.25-2 pbw, prcmoter per 100 pbw silica. In the process according to the invention preference is given to the use of catalysts which have been prepared either by separate impregnation in which first the promoter and then the cobalt is deposited on the silica, or by kneading or a catbination of kneading and impregnation. As regards the promoter present on the catalysts, preference is given to the use of zirconium. The e process according to the invention is preferably carried out at a temperature of 125-350 C and in particular of 175-275 C and a pressure of 5-150 bar and in particular of 10-100 bar. In the process according to the invention the starting material is a H2, CO and H2O-containing feed which preferably has a H2/CO molar ratio higher than 1.75. The process according to the invention may very suitably be carried out as an independent process in which a H2 and CO- containing feed, after the addition of steam, is converted in one step into a hydrocarbon mixture. A very suitable feed may in this case be produced by the addition of steam to a H2/CO mixture obtained by gasification of a carbon-containing material such as coal. The process according to the invention may also very suitably be carried out as part of a multi-step process for the conversion of a H2 and CO-containing feed. This case offers three options, viz A) The process is used as second step in two two-step processes. B) The process is used as the first step of a two-step process. C) A ccmbination of the processes mentioned under A) and B), with the process according to the invention being used as second step in two three-step processes. Each one of these multi-step processes will be further explained hereinafter. In the processes mentioned under A) two embodiments may be distinguished, depending on whether the first step is intended for the preparation of a N /CO mixture with the desired steam content by catalytic conversion of light hydrocarbons (embodiment Al) or whether the first step is intended for the preparation of hydrocarbons and/or oxygen-containing organic compounds by catalytic conversion of a H2/CO mixture (embodiment A2). The process mentioned under Al) bears upon the fact that a very attractive methode of preparing H2/Co mixtures consists in steam reforming light hydrocarbons, such as methane. In this method the light hydrocarbons together with steam are contacted at high temperature and pressure with a catalyst. Catalysts often used for the purpose are nickel-containing catalysts. It is common practice in over to protect the catalysts from excessive coke deposition to carry out this reaction in the presence of an excess of steam, viz. considerably more steam than stoichiometrically required for the comical conversion of the hydrocarbons into a H2/CO mixture. The excess to be used of steam which will ultimately find its way into the ready H2/CO mixture may vary within wide limits. A correct choise of the excess of steam used in the first step will results in the production of a H2/CO mixture which contains the required quantity of steam, so that without any further addition of steam this H2/CO/H2O mixture can be used as the feed for the process according to the invention when used as second step. In the process mentioned under A2) a H2/CO mixture is contacted in the first step with a catalyst containing one or more metal components having catalytic activity for the conversion of a h /CO mixture into hydrocarbons and/or oyygen-containing organic compounds, and unconverted hydrogen and carbon monoxide present in the reaction product of the first step - together with other carpets of that reaction product, if desired - after the addition of steam, are used as the feed for the process according to the invention. Depending on the nature of the catalyst chosen in the first step either substantially aromatic hydrocarbons, or substantially paraffinic hydrocarbons, or substantially cxygen- containing compounds may be prepared in this step. If it is the object in the first step to prepare substantially aromatic hydro carbons, then use may quite suitably be made of a catalyst mixture containing either a methanol or dimethyl ether synthesis catalyst or a Fe/Mg/A1203 or Fe/Cr/SiO2 catalyst prepared by im- pregnation together with a crystalline metal silicate which is characterized in that after one hour's calcination in air at 500 C it has the following properties: : a) an X-ray powder diffraction pattern in which the strongest lines are the lines mentioned in Table A VIABLE A o d(A) 11.1 + 0.2 10.0 i 0.2 3.84 + 0.07 3.72 + 0.06, and b) in the formula which represents the composition of the silicate expressed in moles of the oxides and in which, in addition to SiO2, one or more oxides of a trivalent metal M, chosen fran the group formed by aluminium, iron, gallium, rhodium, chrmium and scandium are present, the SiO2/M2O3 molar ratio is higher than 10. If it is the object in the first step of the two-step process mentioned under A2) to prepare substantially paraffinic hydro- carbons then use may very suitably be made of the above-mentioned Fe/Ng/A1203 or Fe/Cr/SiO2 catalysts prepared by impregnation. If the first step of the two-step process mentioned under A2) is carried cut with the object of preparing oxygen-containing organic compounds, then use may very suitably be made of a methanol or dimethyl ether synthesis catalyst. Methanol synthesis catalysts suitable for use in the first step of the two-step process mentioned under A2) are ZnO/Cr203 and Cu/ZnO/Cr203 catalysts. A dimethyl ether synthesis catalyst suitable for use in the first step of the two-step process mentioned under A2) is a mixture of gamma-Al2O3 and the Cu/ZnO/Cr2O3 methanol synthesis catalyst mentioned hereinbefore. In the two-step process mentioned under B) as well as in the three-step processes mentioned under C) the fact is utilized that the high-beiling part of the product obtained in the process according to the invention can be converted in a high yield into middle dis'tillates using a catalytic hydrotreatment. In the present patent application the term "middle distillates" is used to designate hydrocarbon mixtures whose boiling range corresponds substantially with that of the kerosine and gas oil fractions obtained in the conventional atmospheric distillation of crude mineral oil. Said distillation is used to separate fran crude mineral oil one or more gasoline fractions having a boiling range between 30 and 200 OC, one or more kerosine fractions having a boiling range between 140 and 300 C and one or more gas oil fractions having a boiling range between 180 and 370 OC, successively. The two-step process mentioned under B) comprises carrying cut the process according to the invention as the first step, followed by a catalytic hydrotreatmEnt as the second step. The three-step processes mentioned under C) carprise carrying out the two-step processes mentioned under Al) and A2), with the process according to the invention forming the second steps followed by a catalytic hydrotreatment as the third step. The feed chosen for the catalytic hydrotreai=tnt is at least the part of the reaction product of the process according to the invention whose initial boiling point lies above the final boiling point of the heaviest middle distillate desired as final product. The hydrotreatment which is characterized by a very low hydrogen consumption yields middle distillates with a considerably lower poor point than that of those obtained in the direct Fischer-Tropsch conversion of a N /CO mixture have. Catalysts very suitable for carrying out the catalytic hydrotreatment are those containing one or more noble metals of Group VIII supported on a carrier, and particularly suitable is a catalyst containing platinum supported on a carrier 13-15 %w of which consists of alumina, the rest of silica. The invention is now illustrated with the aid of the following example. EXAMPLE Eight catalyst (catalyst 1-8) were prepared. Catalyst 1 contained 25 pbw iron, 1.25 pbw copper and 2 ptw potassium per 100 pbw silica. Catalyst 2 contained 25 pbw cobalt per 100 pbw silica. Catalysts 3-7, in addition to 25 pbw cobalt per 100 pow silica, contained varying quantities of zirconium. Catalyst 8 contained 25 pbw cobalt and 0.9 pow titanium per 100 pbw silica. All the catalysts were prepared starting frcan the same silica carrier. All the impregnations were carried out as dry impregnations. After each impregnation step the compositions obtained were dried at 120 C and calcined in air at 500 OC. After the last calcination step the compositions were reduced in hydrogen; catalyst 1 at 280 C and the other catalysts at 250 OC. Further information concerning the preparation of the catalysts is given hereinafter. Catalyst 1 One-step impregnation of the silica carrier with an aqueous solution containing both iron nitrate, caper nitrate and potassium nitrate. Catalyst 2 Kneading of a mixture comprising the silica carrier, water and cobalt nitrate. The mixture contained a quantity of water corresponding with 150 %v of the pore volute of the carrier. After 3.5 hours of kneading the kneaded mass was dried at 120 C and calcined in air at 500 OC, Catalyst 3 A boiling solution of cobalt nitrate in water was added with stirring to a boiling solution of soda in water. Then, to the mixture thus obtained soda and the silica carrier were added in succession. After filtration of the mixture the filter cake was washed, dried at 120 C and calcined in air at 500 oC. The composition thus obtained was impregnated in one step with an aqueous solution of zirconium nitrate. Catalyst 3 contained 0.9 etc zirconium per 100 pbw silica. Catalyst 4 Impregnation of the silica carrier first in one step with an aqueous solution of cobalt nitrate and then in one step with an aqueous solution of zirconium nitrate. Catalyst 4 contained 0.9 Fbw zirconium per 100 pbw silica. Catalyst 5 The Co/SiO2 composition the preparation of which has been described under catalyst 2 was lmpregnated in one step with an aqueous solution of zirconium nitrate. Catalyst 5 contained 0.9 pbw zirconium per 100 pbw silica. Catalyst 6 and 7 One-step or rtulti-step impregnation of the silica carrier with a solution of zirconium tetrapropoxide in a fixture of prppanol and benzene, followed by impregnation in one-step with an aqueous solution of cobalt nitrate. In the preparation of catalysts 6 and 7 the impregnation of the silica carrier with the zirconium tetrapropcxide solution was carried out in one and three steps, respectively. Per 100 pow silica catalysts 6 and 7 contained 6 and 18 pow zirconium, respectively. Catalyst 8 Impregnation of the silica carrier, first in one step with a solution of tetraisopropyl orthotitanate in a mixture of isopropanol and acetyl acetone and then in one step with an aqueous solution of cobalt nitrate. Catalyst 8 contained 0.9 pow titanium per 100 pbw silica. The cobalt loads and surface areas of the catalysts 4-8 are given in Table B. Of the above-described catalysts 1-8 only catalysts 4-8 are suitable to be used in the process according to the invention. The other catalysts fall outside the scope of the invention. They have been included in the patent application for comparison. Catalysts 1-8 were used in thirty experiments (Experiments 1-30) in the preparation of hydrocarkons from mixtures of carbon monoxide and hydrogen. The experiments were carried out in a 50 ml reactor containing a fixed catalyst bed of 7.5 ml volume. The conditions under which the experiments were carried out and the results of the experiments are listed in Table C. Of the experiments mentioned in Table C Experiments 10, 11, 15, 16, 20, 22, 24, 26, 28 and 30 are experiments according to the invention. In these experiments the Zr or Ti-promoted Co/SiO2 catalysts which had been prepared by depositing cobalt and the pratoter on the silica carrier by impregnation and/or kneading, were used for the production of hydcccarbons fran H2/CO mixtures containing 20-33 %v of steam, calculated on the H2/CO/H2O mixture. In these experiments relative selectivity gains were obtained of 17-31 %. The other experiments fall outside the scope of the invention. They have been included in the patent application for comparissn. In Experiments 1-3 an iron catalyst was used; in Experiments can unpromoted cobalt catalyst was used; in Experiments 7 and 8 a cobalt catalyst prepared substantiaI1y by precipitation was used. In Experiments 9, 12, 13, 19, 21, 23, 25, 27 and 29 the feed used was a N2/CO mixture to which no steam had been added. In Experiments 14 and 17 the feed used was a H2/c0 mixture containing too little and too much steam, respectively. In these experiments no significant relative selectivity gain was obtained. In Experiment 18 the amount of steam was far too large, which resulted in a drop of C3 selectivity. Catalytic hydrotreatuent An Experiment 31 was carried out in which the Cs fraction of the product obtained according to Experiment 26 was passed together with hydrogen through a 50-ml reactor containing a fixed catalyst bed, at a temperature of 345 OC, a pressure of 130 bar, a space velocity of 1.25 1.1-1.h-1 and a hydrogen/oil ratio of 2000 N1.1-1. The catalyst was a Pt/SiO2-Al203 catalyst containing 0.82 parts by weight platinum per 100 pbw of carrier, which carrier consisted of 14.6 % by weight of alumina and 85.4 % by weight of silica. The results of Experiment 31 are given in Table D. Frcm the results given in Table D it appears that when a catalytic hydrotreatment is applied to a product prepared according to the invention, a considerable part of the 400 C+ fraction is converted (a decrease from 44 to 16 %w) and a considerable quantity of 150-360 C fraction is formed (an increase from 36 to 58 %w), whereas only very little 150 C fraction is formed (an increase fran 12 to 17 %w). TABLE B Catalyst No. 4 5 6 7 8 Cobalt load, mg cobalt llS 130 105 105 118 per ml catalyst Surface area, 22 15 30 28 21 2 m per ml catalyst TABLE C Experiment No. 1 2 3 4 5 6 7 8 9 10 Catalyst No. 1 1 1 2 2 2 3 3 4 4 Temperature, C 250 250 249 250 252 253 250 255 250 250 Pressure, bar 30 30 30 30 30 30 30 30 30 30 Space velocity, 1(H2 + CO).1-1.h-1 1000 1000 1000 1500 1500 1500 3000 3000 3000 3000 H2/CO molar ratio of feed 1 1 1 1 1 1 1 1 1 1 H2O present in feed, %v on (H2 + CO + H2O) 0 5 30 0 20 33 0 20 0 20 CO conversion, %v 39 8 5 35 35 34 32 31 37 35 C3+ selectivity, calculated on C1+, %w 87 71 67 84 84 84 83 81 85 89 Relative selectivity gain, calculated on difference between theoretically attainable C3+ selectivity - * * - 0 0 - * - 27 (100 %) and actual C3+ selectivity without steam addition, % Experiment No. 11 12 13 14 15 16 17 18 19 20 Catalyst No. 4 4 5 5 5 5 5 5 5 5 Temperature, C 252 252 219 220 221 222 224 224 238 240 Pressure, bar 30 30 20 20 20 20 20 20 20 20 Space velocity, 1(H2 + CO).1-1.h-1 3000 3000 1200 1200 1200 1200 1200 1200 4000 4000 H2/CO molar ratio of feed 1 1 3 3 3 3 3 3 3 3 H2O present in feed, %v on (H2 + CO + H2O) 20 0 0 5 20 33 50 60 0 33 CO conversion, %v 37 39 79 80 80 79 80 78 59 60 C3+ selectivity, calculated on C1+, %w 88 84 82 83 85 86 83 78 63 73 Relative selectivity gain, calculated on difference between theoretically attainable C3+ selectivity 20 - - 6 17 22 6 * - 27 (100 %) and actual C3+ selectivity without steam addition, % * selectivity decrease TABLE C (Cont'd) Experiment No. 21 22 23 24 25 26 27 28 29 30 Catalyst No. 5 5 6 6 7 7 7 7 8 8 Temperature, C 250 253 204 205 205 207 221 222 248 251 Pressure, bar 30 30 20 20 20 20 20 20 30 30 Space velocity, 1(H2 + CO).1-1.h-1 3000 3000 2000 2000 2000 2000 3000 3000 3000 3000 H2/CO molar ratio of feed 2 2 3 3 3 3 3 3 1 1 H2O present in feed, %v on (H2 + CO + H2O) 0 25 0 20 0 30 0 20 0 30 CO conversion, %v 65 65 60 60 71 72 81 81 38 39 C3+ selectivity, calculated on C1+, %w 78 83 87 90 87 91 80 85 84 87 Relative selectivity gain, calculated on difference between theoretically attainable C3+ selectivity - 23 - 23 - 31 - 25 - 19 (100 %) and actual C3+ selectivity without steam addition, % D Composition, C1+ product of C5+ fraction C1+product Experiment 26 of the C1+ after the product of catalytic %w Experiment 26 hydrotreatment C4- 16 - 2 C5-150 C 10 12 15 150-250 C 13 16 25 250-360 C 17 20 33 360-400 C 7 8 9 400 C+ 37 44 16

Claims: CLAIMS 1. A process for the preparation of hydrocarbons by catalytic reaction of carbon monoxide with hydrogen, characterized in that a feed which comprises hydrogen, carbon monoxide and steam and in which the quantity of steam present is 10-40 %v calculated on the H2/CO/H2O mixture, is contacted at elevated temperature and pressure with a catalyst which comprises 5-40 pbw cobalt and 0.1-150 pbw of a promoter chosen from the group formed by zirconium, titanium or chromium per 100 pbw silica and has been prepared by depositing cobalt and the promoter on a silica carrier by impregnation and/or kneading and calcining and reducing the composition obtained. 2. Process as claimed in claim 1, characterized in that the catalyst catprises zirconium as a promoter. 3. A process as claimed in claim 1 or 2, characterized in that it is carried out at a temperature of 125-350 C and a pressure of 5-150 bar. 4. A process as claimed in any one of claims 1-3, characterized in that it is used as part of a nulti-step process for the conversion of a H2 and CO-containing feed. 5. A process as claimed in claim 4, characterized in that it is used as the second step of a two-step process in which light hydrocarbons, together with an excess of steam, are subjected in the first step to catalytic steam reforming and in which the H2/CO/H2O mixture thus obtained is used as the feed for the second step. 6. A process as claimed in claim 4, characterized in that it is used as the second step of a two-step process in which a h /CO mixture is contacted in the first step with a catalyst comprising one or more metal components with catalytic activity for converting a H2/CO mixture into hydrocarbons and/or oxygencontaining organic compounds and in which unconverted H2 and CO present in the reaction product. of the first step - together with other components of that reaction product, if desired - after the addition of steam, are used as the feed for the second step. 7. A process as claimed in claim 4, characterized in that it is used as the first step of a two-step process for preparing middle distillates from a H2 and CO-containing feed, in which at least the part of the reaction product of the first step whose initial boiling point lies above the final boiling point of the heaviest middle distillate desired as end-product is subjected in the second step to a catalytic hydrotreatment. 8. A process as claimed in claim 4, characterized in that it is used as the second step of a three-step process for preparing, inter alia, middle distillates from a n2 and CO-containing feed, in which the catalytic hydrotreatment mentioned in claim 7 is the third step applied to relevant heavy fraction of the reaction product of the second step of the two-step process mentioned in claims 5 and 6. 9. A process for the preparation of hydrocarbons by catalytic reaction of carbon nxzxaxide with hydrogen as claimed in claim 1, substantially as described hereinbefore and in particular with reference to the example. 10. Hydrocarbons whenever prepared according to a Process as described in claim 9.

Inventors: MINDERHOUD, JOHANNES KORNELIS, POST, MARTIN FRANCISCUS MARIA, SIE, SWAN TIONG
Applicants: SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V.
Application year: 1983
Main classification: C07C1
IPC codes: B01J27, C07C1, C07C67, C10G2, B01J23