Steam treatment of regenerated catalysts employed in the conversion of hydrocarbons

Claim 1

IN A PROCESS FOR THE CATALYTIC CRACKING OF GAS OIL TO FORM GASOLINE RANGE HYDROCARBONS WHEREIN A SUBDIVIDED SYNTHETIC SILICA-ALUMINA CRACKING CATALYST OF FLUIDIZABLE PARTICLE SIZE IS CIRCULATED IN A SYSTEM COMPRISING A CRACKING ZONE IN WHICH SAID GAS OIL IS CRACKED AT A CRACKING TEMPERATURE IN CONTACT WITH A DENSE, TURBULENT, FLUIDIZED MASS OF SAID CATALYST RESEMBLING A BOILING LIQUID WITH CONCOMITANT DEPOSITION OF COMBUSTIBLE CARBONACEOUS DEPOSITS ON THE CATALYST AND A CATALYST REGENERATION ZONE IN WHICH THE CATALYST IS REGENERATED AT A TEMPERATURE OF ABOUT 100*-1200* F. BY BURNING COMBUSTIBLE CARBONACEOUS DEPOSITS OFF SAID CATALYST WHILE IN THE FORM OF A DENSE, TURBULENT, FLUIDIZED MASS RESEMBLING A BOILING LIQUID AND WHEREIN THE SELECTIVITY OF SAID CATALYST TOWARD THE FORMATION OF GASOLINE RANGE HYDROCARBONS IS REDUCED IN THE COURSE OF SAID PROCESS BY EFFECTS OTHER THAN SAID DEPOSITS, BY FIRST CIRCULATING HIGHLY SELECTIVE CRACKING CATALYST THROUGH SAID CRACKING ZONE AND THROUGH SAID REGENERATION ZONE A NUMBER OF TIMES UNTIL THE SELECTIVITY OF THE CIRCULATING CATALYST IS SUBSTANTIALLY REDUCED, THE IMPROVEMENT WHICH COMPRISES THEREAFTER WITHDRAWING AT INTERVALS A SEPARATE STREAM OF CATALYST OF REDUCED GASOLINE SELECTIVITY FROM SAID REGENERATION ZONE, SAID