Catalytic cracking of mineral hydrocarbon oil

Claim 1

IN A METHOD FOR CONVERTING TO GASOLINE MINERAL HYDROCABON OIL BOILING ABOVE THE GASOLINE RANGE THE STEPS CONSISTING ESSENTIALLY OF HYDROTREATING THE MINERAL HYDROCARBON OIL CONTAINING AT LEAST ABOUT 0.5 P.P.M. NICKEL AND AT LEAST ABOUT 0.5 P.P.M. VANADIUM IN THE PRESENCE OF A HYDROGENATION CATALYST AND MOLECULAR HYDROGEN AT AN ELEVATED TEMPERATURE OF ABOUT 600 TO 900*F. AND SUPERATMOSPHERIC PRESSSURE TO REDUCE PARTIALLY THE CONTENT OF SAID CONTAMINATING METAL BY ABOUT 10 TO 90% WHILE CONSUMING HYDROGEN AND INCREASING THE HYDROGENTO-CARBON RATIO, CONTACTING RESULTING HYDROCARBON PRODUCT BOILING ABOVE THE GASOLINE RANGE AND CONTAINING AT LEAST ABOUT 0.1 P.P.M. NICKEL AND AT LEAST ABOUT 0.3 P.P.M. VANADIUM WITH A SOLID SILICA-BASED CRACKING CATALYST UNDER CRACKING CONDITIONS IN A CRACKING ZONE TO PRODUCE A CONVERSION OF ABOUT 40 TO 70% TO PRODUCTS BOILING IN THE GASOLINE RANGE, PASSING CATALYST FROM THE CRACKING ZONE TO A REGENERATION ZONE WHEREIN CARBON IS BURNED FROM THE CATALYST, PASSING REGENERATED CATALYST TO THE CRACKING ZONE, WITHDRAWING FROM THE CRACKING-REGENERATION SYSTEM CONTAMINATED CATALYST CONTAINING AT LEAST ABOUT 50 P.P.M. NICKEL AND AT LEAST ABOUT 50 P.P.M. VANADIUM, DEMETALLIZING WITHDRAWN CATALYST TO REMOE ABOUT 10 TO 90% OF SAID METAL IMPURITIES AND RETURNING DEMETALLIZED CATALYST TO THE CRACKING SYSTEM.