Catalyst demetallization

Claim 1

IN A METHOD FOR TREATING A SYNTHETIC GEL, SILICA-BASED CRACKING CATALYST WHICH HAS BEEN POISONED BY CONTAMINATION WITH A METAL SELECTED FROM THE GROUP CONSISTING OF IRON, NICKEL AND VANADIUM DUE TO USE OF SAID CATALYST IN CRACKING TO GASOLINE AT ELEVATED TEMPERATURE A HEAVIER HYDROCARBON FEEDSTOCK CONTAINING SAID POISONING METAL, THE STEPS WHICH COMPRISE BLEEDING A PORTION OF THE CATALYST CONTAINING SAID POISONING METAL FROM THE HYDROCARBON CRACKING SYSTEM, SAID BLED CATALYST BEING OUT OF CONTACT WITH THE HYDROCARBON FEEDSTOCK, SULFIDING POISONING METAL CONTAINING COMPONENT ON BLED CATALYST BY CONTACT WITH A VAPOROUS SULFIDING AGENT AT A TEMPERATURE OF ABOUT 500 TO 1500*F., CHLORINATING POISONING METAL CONTAINING COMPONENT ON THE SULFIDE CATAYST BY CONTACT WITH CHLORINATING VAPORS AT ABOUT ROOM TEMPERATURE TO 900*F., CONTACTING THE CATALYST WITH A SULFUR-CONTAINING INORGANIC REDUCING AGENT SELECTED FROM THE GROUP CONSISTING OF REDUCING GASES AND AQUEOUS SOLUTIONS OF WATER-SOLUBLE REDUCING AGENTS IN AN AMOUNT SUFFICIENT TO GIVE AN IMPROVEMENT IN CATALYST CRACKING PERFORMANCE, WASHING THE CATALYST WITH AN AQUEOUS MEDIUM HAVING A PH BELOW ABOUT 5 AND SUFFICIENT TO REMOVE METALS AND IMPROVE THE SUBSEQUENT CRACKING PERFORMANCE OF CATALYST AND RETURNING THE RESULTING DEMETALLIZED CATALYST TO A HYDROCARBON CRACKING SYSTEM.