Multiple riser fluidized catalytic cracking process utilizing hydrogen and carbon-hydrogen contributing fragments

Claim 1

A fluidized catalytic cracking process possessing at least a first and a second riser reaction zone at least one stripping zone in which entrained hydrocarbon material is removed from catalyst and at least one hydrothermal catalyst regeneration zone in which spent cracking catalyst is regenerated, which comprises: (a) converting a hydrogen-deficient first heavy hydrocarbon feed in the first riser reaction zone in the presence of at least the first catalyst component of a mixed catalyst composition comprising as said first catalyst component, an amorphous cracking catalyst and/or a large pore crystalline cracking catalyst and, as a second catalyst component, a shape selective medium pore crystalline silicate zeolite, to provide gasoline boiling range material and one or more light hydrocarbons; (b) converting a hydrogen-rich hydrocarbon feed in a lower region of the second riser reaction zone in the presence of the second component of the mixed catalyst composition to provide gasiform material contributing mobile hydrogen species and/or carbon-hydrogen fragments for combination with a thermally treated, relatively hydrogen-deficient second heavy hydrocarbon feed introduced to an upper region of the second riser reaction zone; and (c) converting the gasiform material and thermally treated, relatively hydrogen-deficient second heavy hydrocarbon feed in an upper region of the second riser reaction zone in the presence of the mixed catalyst composition under conditions affecting cracking and additive carbon-hydrogen reactions to provide a gasoline product of increased octane number and/or higher quality, there being a sufficient difference in average particle density, particle size and/or particle geometry of the catalyst components as to confer a higher average settling rate upon particles of second catalyst component compared to that of particles of first catalyst component with the result that particles of second catalyst component will possess a longer residence time in the lower region of the second riser reaction zone compared to that of particles of first catalyst component, the second catalyst component additionally defining a zone of concentration in said lower region.