Passivation of metal contaminants on cracking catalyst with a lithium compound

A process for passivating a metal on fluidized cracking catalyst which has been contaminated with said metal due to the use of said catalyst in a fluidized cracking system and wherein said catalyst is cycled between a cracking zone, in which said catalyst is contacted at an elevated temperature with a hydrocarbon feedstock containing said metal contaminant which deposits on said catalyst, and a regeneration zone, in which carbon is oxidized and thereby removed from said catalyst, which process comprises contacting at least a portion of said catalyst at passivation reaction conditions with a lithium compound in an amount to deposit on the catalyst about 0.5 wt % to 1.25 wt % lithium on an elemental metal basis, to effect a passivation reaction between said metal and said lithium and the passivation of said metal contaminant so as to increase yield of C.sub.5.sup.+ and reduce the yield of hydrogen in said fluidized cracking system.