Process for preparing gasoline range hydrocarbons from synthesis gas and catalyst used therefor

A process for the conversion of synthesis gas consisting essentially of CO and hydrogen to a product high in branched chain paraffins and olefins in the gasoline boiling range, which comprises contacting said synthesis gas under conversion conditions with a catalyst consisting essentially of an admixture of (A) silicalite and (B) cobalt on a high surface area, high purity, low acidity alumina support of gamma-alumina, eta-alumina or mixtures thereof, said catalyst component (B) 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.