GB982610A - Hydrocracking process - Google Patents

Abstract

A two-stage hydrocracking of hydrocarbon distillates boiling in the range 500-1100 DEG F. or residua boiling above 1050 DEG F. is effected in a first stage at a conversion of 10-50% volume of feed to products boiling below the initial boiling point of the feed at 550-900 DEG F., a LHSV of 0.1-3 and a hydrogen partial pressure of 500-3000 p.s.i.g. over a catalyst comprising a hydrogenating-dehydrogenating component alone or deposited on a support of no more than weak acidity and at least part of the effluent is treated in the second zone at a conversion of at least 20% volume to products boiling below the initial boiling point of feed to that zone at 450-850 DEG F., a LHSV of 0.2-5 and a hydrogen partial pressure of at least 350 p.s.i.g. with a catalyst comprising a hydrogenating-dehydrogenating component on a strongly acidic active cracking support. The first zone gives high yields of middle distillate product and the second zone high yields of naphtha and by adjustment of the feed to the second zone and recycles yields of naphtha or of middle distillate can be increased or decreased according to requirements. The hydrogenating-dehydrogenating catalyst in each zone is a metal, or oxide, sulphide or selenide thereof, of Group VI or VIII, or combinations thereof, particularly sulphides of cobalt and/or nickel with sulphides of molybdenum and/or tungsten. In the first zone the support may be a single refractory oxide (not mixed oxides) e.g. silica, alumina, titania, zirconia, kieselguhr or bauxite or charcoal. Mixed oxides may be used in the second zone, e.g. silica-alumina, or activated alumina, alumina, alumina-BF3 combinations or various fluorided or selenided supports. The product from the first zone is fractionated to recover a naphtha product boiling below 400 DEG F. and optionally a middle distillate product. Material boiling above 320 DEG F. is at least partially passed to the second zone, e.g. that boiling above 500 DEG F. and part may also be recycled to the first zone. Product from the second zone is also fractionated, optionally in the same apparatus, to recover naphtha and middle distillate products and material boiling above the initial boiling point of the feed to the second zone may be recycled through the second zone. U.S.A. Specification 2,944,006 is referred to.ALSO:A catalyst for use in the first stage of a two-stage hydrocarbon hydrocracking process comprises a metal or an oxide, sulphide or selenide thereof of Group VI or VIII, e.g. Co, Ni, Mo and W, supported on a support of no more than weak acidity, e.g. a single refractory oxide, while in the second stage a similar hydrogenating-dehydrogenating component is used on a strongly acidic active cracking support, e.g. charcoal, TiO2, ZrO2, Kieselguhr, bauxite, activated alumina, alumina-BF3 or fluorided or selenided supports.