Method for improving the Fischer-Tropsch synthesis product distribution

A method of forming hydrocarbons from carbon monoxide and hydrogen which comprises:

• passing carbon monoxide and hydrogen in contact with a Fischer-Tropsch synthesis carbon monoxide reduction catalyst under temperature and pressure conditions promoting the formation of hydrocarbons and oxygenates,
• separating the Fischer-Tropsch synthesis product into a hydrocarbon fraction boiling below about 400.degree. F. and a hydrocarbon fraction boiling above about 400.degree. F.,
• passing said hydrocarbon fraction boiling below about 400.degree. F. in contact with a crystalline zeolite that has a pore diameter greater than about 5 angstroms;
• a silica to alumina ratio of at least 12;
• a constraint index within the range of 1-12;
• under temperature and pressure conditions promoting the formation of gasoline boiling range products of higher octane rating, passing said hydrocarbon fraction boiling above 400.degree. F. sequentially in contact with a hydrogenation catalyst maintained under relatively mild hydrogenation conditions and then in contact with a crystalline zeolite that has a pore diameter greater than about 5 angstroms;
• a silica to alumina ratio of at least 12;
• a constraint index within the range of 1-12;
• maintained under conditions to convert said hydrocarbon fraction to a lower boiling fuel oil product of reduced pour point, and
• recovering gasoline boiling range products from each of said crystalline zeolite conversion operations of a higher octane rating than the octane rating of gasoline product of Fischer-Tropsch synthesis.