GB593910A - Improved process for the catalytic synthesis of hydrocarbons from carbon monoxide and hydrogen - Google Patents

Abstract

A catalyst comprising nickel chromite, used in the production of hydrocarbons containing more than one carbon atom per molecule from carbon monoxide (see Group IV) and hydrogen, is prepared by adding a solution of ammonium dichromate in water and ammonium hydroxide to an aqueous solution of nickel nitrate maintained at about 165 DEG F., the resultant precipitate being filtered, dried at 300 DEG F. and then calcined at 700 DEG F. Other nickel salts, e.g., the chloride, carbonate and sulphate may be employed. In the latter case any sulphate ions present in the catalyst should be removed. Chromic acid and ammonium hydroxide, ammonium chromate, or sodium and potassium chromates and dichromates may be employed instead of the ammonium dichromate. The nickel chromite may be pelleted or employed on a suitable carrier such as silica gel, alumina gel, diatomaceous earth, kieselguhr, activated charcoal and for this purpose the catalyst may be precipitated within the carrier and the catalyst impregnated carrier then calcined. The nickel chromite may also be coated on the carrier and calcined and reduced as a coating on the carrier. The catalyst either alone or on a porous or gelatinous carrier may be used in fluid operation. In two examples the catalyst employed in the reaction of carbon monoxide with hydrogen is prepared by reducing the nickel chromite obtained as above with a large excess of hydrogen at temperatures of 760 DEG F. and 750 DEG F. respectively. The nickel chromite reduced by hydrogen comprises a catalytic mixture of metallic nickel and chromium.ALSO:Hydrocarbons containing more than one carbon atom per molecule are produced by reacting carbon monoxide and hydrogen at temperatures of 300-450 DEG F. and at atmospheric or elevated pressures in the presence of a catalyst comprising nickel chromite and/or a mixture of metallic nickel and chromium obtained by reducing nickel chromite with hydrogen. The catalyst may be prepared (see Group III) by adding a solution of ammonium dichromate in water and ammonium hydroxide, to an aqueous solution of nickel nitrate and drying and calcining the resultant precipitate. Instead of ammonium dichromate, chromic acid and ammonium hydroxide, ammonium chromate or sodium and potassium chromates and di-chromates may be used. Other nickel salts, e.g. the sulphate, chloride and carbonate may be used, but when nickel sulphate is employed, precautions should be taken to remove any sulphate ions present in the precipitated catalyst. The catalyst may be pelleted or employed on a suitable carrier such as silica gel, alumina gel, diatomaceous earth, kieselguhr and activated charcoal. The nickel chromite may also be coated on the carrier and calcined and reduced as a coating on the carrier. The nickel chromite prepared by calcination of the nickel ammonium chromate complex is suitable for use in fluid operation and the catalyst has been found to fluidize readily when prepared on a carrier such as silica gel, alumina, clay, bauxite, silica-alumina gels and kieselguhr. The feed stock which should be freed from sulphur and sulphur compounds, e.g. by treatment with caustic alkali or tri-ethanolamine, may be supplied from such sources as water gas, gases obtained through the controlled hydrogenation of coal or by gasification of solid carbonaceous fuel such as coke, brown coal and mineral oil, or by the conversion of natural gas, by the reaction of methane with steam and/or carbon dioxide or subjecting hydrocarbon gases to controlled and incomplete combustions. In two examples, the catalyst prepared as above is reduced with a large excess of hydrogen at 760 DEG F. and 750 DEG F. respectively, and a mixture of carbon monoxide and hydrogen passed through a reactor containing the catalyst. The temperature of the reactor is about 360 DEG F. and the throughput is 118 volumes and 111-113 volumes of gaseous synthesis mixture per volume of catalyst per hour respectively, liquid hydrocarbons being obtained.