GB928794A - Low temperature hydrocracking process - Google Patents

Abstract

In the hydrocracking of a hydrocarbon distillate feed low in nitrogen compounds and containing aromatics, the feed is first hydrogenated catalytically to saturate at least 50% of the aromatics and thereafter is hydrocracked by contact with hydrogen and an acidic cracking catalyst having hydrogenating characteristics at 350 DEG -700 DEG F. and at least 400 p.s.i.g. to consume at least 250 SCF of hydrogen per barrel of the feed to product fractions boiling below the initial boiling point of the feed. The feed may be a heavy naphtha, kerosene, light or heavy gas oil, light or heavy coker distillate, light or heavy cycle oil, heavy catalytic reformate or aromatic extracts from various fractions. The total nitrogen content is first reduced to below 10 p.p.m. by conventional hydrofining followed by removal of hydrogen sulphide and ammonia. Hydrogenation of aromatics is effected over a metal of Group 6, 7, or 8 or oxide thereof, preferably platinum, supported on alumina, silica or kieselguhr, at 300 DEG -700 DEG F. at least 300 p.s.i.g. and LHSV of 0,3-5 using at least 2000 SCF of hydrogen per barrel of feed. The total effluent can be passed to the hydrocracking which may be effected in a separate part of the same apparatus or hydrogen can be separated and various products separated. The cracking catalyst is preferably a solid siliceous material, e.g. silica-alumina, silica-magnesia,silica-alumina-zirconia, acid treated clays or a synthetic chabazite, or may be alumina-aluminium chloride, fluorided magnesia, charcoal-alumina, or liquids, e.g. hydrogen fluoride-boron trifluoride, titanium tetrachloride, or aluminium chloride-hydrogen chloride-hydrocarbon. With this is associated a hydrogenating component which may be a metal or oxide or sulphide thereof of Group 1b, 2b, 5, 6, 7 or 8 in an amount of 0,1-35% of the composition. Preferred are cobalt and/or nickel sulphide on silica-alumina. At least 500 SCF of hydrogen per barrel of feed (including recycle) is present. The pressure may be 500-2000 p.s.i.g. and the LHSV 0,2-5. The product is separated into hydrogen, C1-C3 or C4, gasoline which may be reformed and jet fuel, bottoms being recycled.