Abstract

A catalytic cracking process is provided featuring multiple risers in which a variety of hydrocarbon conversion reactions take place, a stripping unit in which entrained hydrocarbon material is removed from catalyst and a regeneration zone in which spent cracking catalyst is regenerated, which comprises:(a) converting a relatively high boiling hydrocarbon charge material in a first riser in the presence of a first catalyst component which is an amorphous cracking catalyst and/or a large pore crystalline zeolite cracking catalyst to provide lighter products;(b) converting an ethylene-rich charge material introduced to a second riser at a lower level thereof in the presence of a second catalyst component which is a shape selective medium pore crystalline silicate zeolite catalyst to provide heavier products and to increase the temperature of the catalyst in said region; and,(c) converting a naphtha charge material introduced to the second riser at a higher level thereof in the presence of said second catalyst component to provide a relatively high octane gasoline product.