Catalyst treatment and flow conditioning in an fcc reactor riser

Abstract

A process for converting a charge stock comprising normally liquid hydrocarbons in a riser conversion zone with an active fluid catalytic cracking catalyst wherein a suspension of hot regenerated active fluid catalytic cracking catalyst in a lift gas comprising hydrocarbons including not more than 10 mole % C.sub.3 and heavier hydrocarbons (calculated on a water-free basis) is passed through a first treatment section of the riser conversion zone at conditions selected to treat the catalyst prior to any contact with the charge stock while simultaneously accelerating the catalyst to a velocity sufficient to provide turbulent dilute flow at the point of contact with the charge stock; thereafter a charge stock is introduced into the suspension of treated particles in the riser conversion zone downstream of the treatment section to form a mixture of catalyst, charge stock and lift gas having the catalyst relatively uniformly distributed therethrough. The charge stock is then reacted with the catalyst in the remaining downstream section of said riser conversion zone at reaction conditions sufficient to effect the desired conversion.