Cracking a plurality of hydrocarbon stocks

Claim 1

IN THE CRACKING OF A PLURALITY OF MINERAL OIL HYDROCARBON CHARGE STOCKS IN THE PRESENCE OF A FINELY DIVIDED SOLID SYNTHETIC GEL, SILICA-BASED CRACKING CATALYST, AT LEAST ONE OF SAID CHARGE STOCKS BEING METAL-CONTAMINATED AND CONTAINING MORE THAN ABOUT 1.5 PARTS PER MMILLION OF VANADIUM AND MORE THAN ABUOT 0.6 PART PER MILLION OF NICKEL AND AT LEAST ONE OF SAID CHARGE STOCKS BOILING IN THE GAS OIL RANGE AND BEING RELATIVELY METALS-FREE, CONTAINING LESS THAN ABOUT 0.5 PART PER MILLION OF VANADIUM AND LESS THAN ABOUT 0.2 PART PER MILLION OF NICKEL, THE STEPS COMPRISING CONDUCTING THE CRACKING UNDER FLOW CONDITIONS OF PROGRESSIVE REACTION IN A REACTION ZONE BY CONTACTING THE CATALYST UNDER CRACKING CONDITIONS FIRST WITH THE SAID RELATIVELY CONTAMINANT-FREE CHARGE STOCK IN VAPOR FORM WHILE FLOWING THE CATALYST AND VAPOR IN SUSPENSION THROUGH AN ELONGATED CONFINED REACTION FLOW PATH IN THE REACTION ZONE, INTRODUCING SAID CONTAMINATED CHARGE STOCK INTO THE LAST ONE-FOURTH OF SAID FLOW ATH TO CRACK SAID CONTAMINATED STOCK AND DEPOSIT METAL POISONS ON THE CATALST, SEPARATING CATALYST FROM HYDROCARBONS AT THE END OF THE FLOW PATH AND RECOVERING HYDROCARBON PRODUCTS, CYCLING THE CATALYST BETWEEN THE REACTION FLOW PATH AND A CATALYST REGENERATION ZONE WHEREIN CARBON IS BURNED FROM THE CATALYST, BLEEDING FROM THE CONVERSION SYSTEM A PORTION OF CATALYST CONTAINING AT LEAST ABOUT 50 P.P.M. NICKEL AND 50 P.P.M. VANADIUM DEMETALLIZING BLED CATALYST AND RETURNING RESULTING DIMETALLIZED CATALYST TO THE CRACKING FLOW PATH.