Desulfurization of crude oil and crude oil fractions

Claim 1

A METHOD FOR DESULFURIZING A NAPHTHENES-CONTAINING PETROLEUM FEED STOCK SELECTED FROM THE GROUP OF CRUDE OILS AND CRUDE OIL FRACTIONS CONTAINING AN APPRECIABLE AMOUNT OF ASH-FORMING CONSTITUENTS INCLUDING THE STEPS OF HEATING SAID SELECTED FEED STOCK TO A TEMPERATURE WITHIN THE RANGE OF 700* TO 850* F. WHEREBY AT LEAST A SUBSTANTIAL PORTION OF SAID FEED STOCK IS VAPORIZED, CONTACTING SAID HEATED FEED STOCK AT A TEMPERATURE WITHIN SAID RANGE IN A FIRST CATALYTIC ZONE WITH A SPENT SILICA-ALUMINA CRACKING CATALYST IN THE PRESENCE OF HYDROGEN IN AN AMOUNT OF 2 TO 40 MOLES PER MOL OF OIL, A PRESSURE IN THE RANGE OF 0 TO 500 POUNDS PER SQUARE INCH GAUGE AND A FEED RATE WITHIN THE RANGE OF 0.5 TO 20 VOLUMES OF LIQUID FEED PER VOLUME OF SAID SPENT CATALYST PER HOUR, REMOVING THE EFFLUENT FROM SAID CATALYTIC ZONE AND CONTACTING IT IN A SECOND CATALYTIC ZONE WITH A GAMMA ALUMINA-SUPPORTED SULF-ACTIVE HYDROGENATION CATALYST AT A TEMPERATURE WITHIN THE RANGE OF 700 TO 850* F., A HYDROGEN RATIO OF 2 TO 20 MOLES PER MOL OF OIL, A PRESSURE WITHIN THE RANGE OF 0 TO 500 POUNDS PER SQUARE INCH GAUGE AND A FEED RATE IN THE RANGE OF 0.2 TO 10.0 VOLUMES OF LIQUID FEED PER VOLUME OF CATALYST PER HOUR, REMOVING EFFLUENT FROM SAID SECOND CATALYTIC ZONE AND RECOVERING A DESULFURIZED OIL PRODUCT, SAID SULF-ACTIVE HYDROGENATION CATALYST BEING SELECTED FROM THE CLASS CONSISTING OF OXIDES AND SULFIDES OF V,CR,MN,FE,CO,NI,MO AND W, AND FIRST CATALYTIC ZONE BEING MAINTAINED AT A TEMPERATURE WITHIN THE RANGE OF 30* TO 60* GREATER THAN THE TEMPERATURE OF THE SECOND CATALYTIC ZONE WHEREBY AT LEAST A PORTION OF SAID NAPHTHENES ARE DEHYDROGENATED, WHEREBY HYDRODESULFURIZATION IS MAXIMIZED AND WHEREBY HYDROCRACKING IS MINIMIZED.