Riser cracking of catalyst-deactivating feeds

Claim 1

In a process for cracking a hydrocarbonaceous feedstock containing a catalyst-deactivating component in the absence of externally supplied hydrogen in contact with an entrained bed of particulate acidic cracking catalyst flowing through a riser-reactor zone, the method for increasing conversion of said feedstock which comprises: (a) maintaining first and second unmixed portions of said catalyst in separated entrained flow through an upstream part of said riser-reactor zone, said first portion having sufficient heat energy to substantially vaporize said feedstock; (b) vaporizing and partially cracking said feedstock in contact with said first portion of said catalyst and decreasing the concentration of said catalyst-deactivating component in said vapor by depositing at least a portion of said catalyst-deactivating component on said first portion of said catalyst in said upstream part of said riser-reactor zone; and (c) mixing said second portion of said catalyst with the resulting hydrocarbonaceous vapor and cracking said hydrocarbonaceous vapor in a downstream part of said riser-reactor zone with said second portion of said catalyst.