Improved zeolite octane additive.

摘要

When a zeolite additive composition of a mediumpore zeolite with a Constraint Index from about 1 to about 12 and a silica to alumina mole ratio greater than about 12 is added to a conventional cracking catalyst dispersed in an inorganic matrix, the octane will be improved, but there will be a yield loss in the amount of gasoline produced. An improvement in that catalyst system is obtained by partially exchanging the medium-pore zeolite additive with cations from one or more elements of Group IA, Group IIA or Group IIIA of the Periodic Table. The octane number of the gasoline-range product of an FCC process is still improved while the amount of the gasoline yield loss typically observed for such octane-enhancing additives is reduced.