Conversion of synthesis gas to diesel fuel and gasoline

A process for the conversion of synthesis gas to diesel fuel and gasoline, which comprises contacting synthesis gas consisting essentially of CO and hydrogen in a synthesis gas conversion zone with a synthesis gas conversion catalyst comprising cobalt and 0 to about 100 parts by weight of a Group IIIB or IVB metal oxide per 100 parts by weight of said cobalt, on a high surface area, high purity, low acidity alumina support of gamma-alumina, eta-alumina or mixtures thereof, said catalyst having a hydrogen chemisorption value of from about 100 to about 300 micromol of hydrogen per gram of total catalyst when measured at 25.degree. C., said catalyst having been prepared by (A) impregnation of said alumina support with a non-aqueous, organic solvent impregnation solution of cobalt nitrate and (B) reduction of said impregnated alumina support by heating, in the presence of hydrogen gas, at a heating rate of from about 0.5.degree. to about 5.degree. C. per minute to a maximum hold temperature in the range of 180.degree. to about 220.degree. C. for a hold time of 6 to about 24 hours and thereafter heating said impregnated alumina support in the presence of hydrogen gas while heating up to a maximum hold temperature of from about 250.degree. to about 400.degree. C. for a hold time of 6 to about 65 hours, to produce a reaction effluent comprising straight chain hydrocarbons boiling in the diesel fuel boiling range and in the C.sub.5 -C.sub.9 range, separating a stream comprising said straight chain paraffins in the C.sub.5 -C.sub.9 range from the reaction effluent and subjecting said separated stream to dehydrocyclization in the presence of hydrogen and a dehydrocyclization catalyst in a dehydrocyclization conversion zone to produce a high octane gasoline product.