Hydrocracking process producing lubricating oil

Claim 1

A PROCESS FOR SUBSTANTIALLY ENTIRELY CONVERTING A HEAVY OIL FEED WHICH HAS (A) A VISCOSITY INDEX OF NOT MORE THAN 35, (B) AN END BOILING POINT OF NOT LESS THAN 1000*F. AND (C) OF WHICH AT LEAST 30% BOILS ABOVE 800*F. TO (I) DISILLATES BOILING BELOW ABOUT 700*F. AND (II) IMPROVED LUBRICATING OIL BASE STOCK BOILING SUBSTANTIALLY ENTIRELY ABOVE 700*F., WHICH PROCESS COMPRISES HYROCRACKING SAID HEAVY OIL FEED IN ADMIXTURE WITH A HEAVY RECYCLE OIL BOILING SUBSTANTIALLY ENTIRELY ABOVE 700*F. AND CONTAINING AT LEAST A SUBSTANTIAL PORTION OF THE HIGHEST BOILING COMPONENTS OF SAID HEAVY OIL FEED IN A CATALYTIC HYDROCRACKING REACTION ZONE AT CONDITIONS FOR CONVERTING BETWEEN 20 AND 40% OF THE COMBINED FEED AND RECYCLE OIL WHICH DOES NOT BOIL BELOW 700*F. TO DISTILLATES BOILING BETWEEN 400* AND 700*F. AND NO MORE THAN AN EQUAL AMOUNT BUT AT LEAST 10% OF THE COMBINED FED AND RECYCLE OIL WHICH DOES NOT BOIL BELOW 700*F. TO DISTILLATES BOILING BELOW 400*F., SAID RECYLCLE OIL BEING SUPPLIED IN A VOLUME RATIO TO HEAVY OIL FEED BETWEEN 0.3 AND 1.5, DISTILLING THE NORMALLY LIQUID HYDROCARBON EFFLUENT OF SAID HYDROCRACKING REACTION ZONE TO SEAPRATE SAID EFFLUENT INTO DISTILLATES BOILING BELOW ABOUT 700*F. AND A REMAINDER BOILING HIGHER THAN SAID REMAINDER FURTHER DISTILLING AT LEAST A PORTION OF SAID REMAINDER TO SEPARATE IT AT LEAST INTO A DISTILLATE LUBRICATING OIL FRACTION AND A RESIDUAL LUBRICATING OIL FRACTION AND RECOVERING FROM LUBRICATING OIL FRACTIONS AT LEAST ONE LUBRICATING OIL BASE STOCK IN A LIMITED YIELD SUCH THAT THE PORTION OF SAID TOTAL LUBRICATING OIL BASE STOCK RECOVERED WHICH BOILS WITHIN THE BOILING RANGE OF SAID HEAVY OIL FEED IS EQUAL IN AMOUNT TO BETWEEN 2% AND 40% OF SAID HEAVY OIL FEED, AND FORMING SAID HEAVY RECYCLE OIL BY COMBINING EACH PORTION OF SAID REMAINDER BOILING SUBSTANTIALLY ENTIRELY ABOVE 700*F. WHICH WAS NOT SO FURTHER DISTILLED WITH EACH PORTION OF THE REMAINDER WHICH WAS SO FURTHER DISTILLED AND BOILS SUBSTANTIALLY ENTIRELY ABOVE 700*F. BUT WAS NOT RECOVERED AS LUBRICATING OIL BASE STOCK, INCLUDING A SUBSTANTIAL PORTION OF SAID REMAINDER BOILING OVER THE SAME BOILING RANGE AS A PORTION RECOVERED AS LUBRICATING OIL BASE STOCK.