GB712686A - Process for the catalytic hydrogenation of carbon monoxide - Google Patents

Abstract

A product of high ester content is obtained by contacting a synthesis gas containing CO and H2, at 165-240 DEG , preferably 190-220 DEG C., and 10-50 kg./sq. cm., with a precipitated iron catalyst containing a halogen-free alkali metal compound introduced into the catalyst in the form of a salt of one of the phosphoric, boric, tungstic or molybdic acids, more than 60 per cent of the iron being in the metallic state and the alkali compound, calculated as K2O, being present in a proportion of 0.5-10, preferably 2-5 per cent, by weight of the total iron. A reducing pretreatment of the catalyst with H2 and/or CO is effected using high gas velocities at 200-320, preferably 250-300 DEG C. The synthesis gas should be rich in CO, and the gas rate may be above 100 up to 500 1. per litre of catalyst per hour. Products containing alcohols, esters, hydrocarbons, and some other oxygenated compounds are obtained. Temperature may increase in the direction of gas flow, and recycling may be employed. In examples, catalysts containing 100 parts Fe and 5 Cu or 100 Fe+25 Cu+20 Cr2O3+20 kieselguhr are made by precipitation from solutions of the nitrates with Na2CO3, washing, and impregnating with potassium phosphate solution to give 7.9 or 2 parts respectively K2O. They are reduced with a mixture of 3H2+1N2 or H2 alone at 300 DEG C. and a flow rate of 1.2 or 1.5 m./sec. to give 62 or 85 per cent reduction of the iron to free metal. Water gas is passed at 10 kg./sq. cm. and 205 DEG C. or 20 kg./sq. cm. and 211 DEG C. to yield hydrocarbons and oxygenated compounds including esters and alcohols.ALSO:A precipitated iron catalyst for CO+H2 synthesis contains a halogen-free alkali metal compound introduced into the catalyst in the form of a salt of one of the phosphoric, boric, tungstic or molybdic acids, more than 60 per cent. of the iron being in the metallic state and the alkali compound, calculated as K2O, being present in a proportion of 0.5-10, preferably 2-5 per cent. by weight of the total iron. A reducing pre-treatment of the catalyst with H2 and/or CO is effected using high gas velocities at 200-320, preferably 250-300 DEG C. In Examples, catalysts containing 100 parts Fe and 5 Cu or 100 Fe+25 Cu+20 Cr2O3+20 kieselguhr are made by precipitation from solutions of the nitrates with Na2CO3, washing, and impregnating with potassium phosphate solution to give 7.9 or 2 parts respectively K2O. They are reduced with a mixture of 3 H2 + 1N2 or H2 alone at 300 DEG C. an a flow rate of 1.2 or 1.5 m/sec. to give 62 or 65 per cent. reduction of the iron to free metal.