Catalytic cracking and regeneration of catalyst

Claim 1

IN THE CATALYTIC CRACKING OF HYDROCARBON OILS FOR THE PRODUCTION OF MOTOR FUEL, THE PROCESS THAT COMPRISES CONTACTING A STOCK CONTAMINATED WITH ORGANO METALLIC COMPOUNDS OF THE NATURE OF CHROMIUM, NICKEL, IRON AND VANADIUM COMPOUNDS WITH SOLID CRACKING CATALYST AT CRACKING TEMPERATURE WITH RESULTANT DEPOSITION OF COKE AND CONTAMINANTS ON THE CATALYST, SUBJECTING THE CATALYST TO NORMAL REGENERATION BY BURNING OF DEPOSITED COKE AT TEMPERATURES NOT OVER 1125* F. AND WITH NOT MORE THAN ABOUT 10% STEAM IN THE REGENERATION GAS AND REUSING THE REGENERATED CATALYST IN THE PROCESS, CONTINUING SUCH OPERATIONS FOR A PERIOD WITH RESULTANT ALTERATION IN THE SELECTIVITY OF THE CATALYST LEADING TO INCREASED FORMATION OF COKE AND GAS DUE TO THE PRESENCE OF THE CONTAMINANTS ON THE CATALYST, THEN SUBSTITUTING AN UNCONTAMINATED STOCK FOR SUCH CONTAMINATED STOCK AND SUBSTITUTING FOR THE NORMAL REGENERATION A CATALYST DEACTIVATING OPERATION IN WHICH THE CATALYST IS SUBJECTED TO REGENERATION AT A TEMPERATURE OF THE ORDER OF 1150* F. IN THE PRESENCE OF THE ORDER OF 50% BY VOLUME OF STEAM IN THE REGENERATING GAS FOR A PERIOD OF 12 TO 72 HOURS TO EFFECT ALTERATION OF THE CATALYST STRUCTURE SO AS TO OCCLUDE DEPOSITED CONTAMINANTS WITHIN THE CATALYST AND REDUCE THE PORE VOLUME AND INCREASE THE DENSITY OF THE CATALYST, THEREAFTER RESUMING NORMAL REGENERATION AT TEMPERATURES NOT OVER 1125* F. AND WITH NOT MORE THAN ABOUT 10% STEAM IN THE REGENERATION GAS AND CONTINUING THE OPERATION FOR AN EXTENDED PERIOD.