1817. ------. [KEITH, P. C.] (Hydrocarbon Research, Inc.). Process for Stripping Spent Fluid Catalysts. Canadian Patent 476,474, Aug. 28, 1951; appl. filed Aug. 11, 1945, Serial No. 530,206; 11 claims.

Fluid catalysts that have become spent in the conversion zone are revivified during the transfer of the spent catalyst from the conversion zone to the regeneration zone by passing a composite gas stream made up of O₂ of not less than 95% purity and a gaseous supplement thereto, which is predominantly a mixture of C oxides with not less than about 35% by vol. of O₂ upward through a substantially vertical elongate zone and simultaneously moving fluidized spent catalyst downward through the same zone, while maintaining a temperature therein below the deactivation temperature of the catalyst but not below about 800º F.