Hydrocracking process with pre-hydrogenation

Claim 1

A PROCESS FOR HYDROCRACKING A MINERAL OIL FEEDSTOCK CONTAINING POLYCYCLIC AROMATIC HYDROCARBONS BOILING ABOVE ABOUT 600*F. AND ORGANIC NITROGEN COMPOUNDS, AND BOILING ABOVE THE GASOLINE RANGE TO PRODUCE THEREFROM HYDROCARBONS BOILING IN THE GASOLINE RANGE, WHICH COMPRISES SUBJECTING SAID FEEDSTOCK TO AN INITIAL HYDROGENATION AT A TEMPERATURE BETWEEN ABOUT 600* AND 850*F. AND IN THE PRESENCE OF A HYDROGENATION CATALYST SELECTED FROM THE CLASS CONSISTING OF THE GROUP VIB AND GROUP VIII METAL SULFIDES SEPARATING AMMONIA AND HYDROGEN SULFIDE FROM THE DENITROGENATED PRODUCT AND FRACTIONATING THE LIQUID PRODUCT TO RECOVER A LIGHT GAS OIL FRACTION BOILING BETWEEN ABOUT 400* AND 600*F. AND A HEAVIER FRACTION, SUBJECTING AT LEAST A PORTION OF SAID HEAVIER FRACTION TO A SECOND HYDROGENATION UNDER NON-CRACKING CONDITIONS IN THE PRESENCE OF A HYDROFINING CATALYST SELECTED FROM THE CLASS CONSISTING OF THE OXIDES AND SULFIDES OF IRON, COBALT, NICKEL AND THE GROUP VIB METALS AND AT AN AVERAGE BED TEMPERATURE WHICH IS (A) LOWER THAN THE AVERAGE BED TEMPERATURE EMPLOYED IN SAID INITIAL HYDROGENATION, AND (B) BETWEEN ABOUT 500* AND 750*F.; THEN SUBJECTING THE HYDROCARBON PRODUCT FROM SAID SECOND HYDROGENATION PLUS SAID LIGHT GAS OIL FRACTION TO CATALYTIC HYDROCRACKING AT A TEMPERATURE BETWEEN ABOUT 400* AND 725*F. IN THE PRESENCE OF A HYDROCRACKING CATALYST COMPRISING A GROUP VIII METAL HYDROGENATING COMPONENT, AND UNDER CONDITIONS ADJUSTED TO GIVE AT LEAST ABOUT 30% CONVERSION PER PASS TO 400*F. END-POINT GASOLINE, RECOVERING GASOLINE-BOILINGRANGE HYDROCARBONS FROM THE HYDROCRACKED PRODUCT, AND CONTINUING SAID CATALYTIC HYDROCRACKING FOR A TOTAL OPERATING PERIOD OF AT LEAST ABOUT 4 MONTHS WITHOUT REGENERATION OF SAID HYDROCRACKING CATALYST, SAID INITIAL HYDROGENATION, SAID SECOND HYDROGENATION AND SAID HYDROCRACKIG STEP ALL BEING CONDUCTED AT PRESSURES BETWEEN ABOUT 500 AND 3,000 P.S.I.G.