Partial CO combustion with staged regeneration of catalyst

FCC catalyst is regenerated in a process providing increased coke-burning capacity without additional heat evolution or air consumption. The process uses a two-stage regeneration arrangement providing initial coke combustion in a low catalyst density-high efficiency contact zone followed by substantial separation of catalyst and regeneration gas and complete regeneration of catalyst particles in a dense bed regeneration zone. Catalyst and gas flow cocurrent prior to this separation but flow countercurrent after the separation. An effective control scheme for regulating oxygen addition to the final zone is also disclosed. This process is applicable to FCC operations for conventional and residual feedstocks.