LUBRICATING OIL BASE STOCK PRODUCTION

1353950 Hydrocracking; luboil bases UNIVERSAL OIL PRODUCTS CO 19 April 1971 [2 April 1970 (2)] 25822/71 Heading C5E Lubricating oils of V.I. higher than 100 are obtained by cracking two feedstocks. The first feed, e.g. a deresined cylinder stock, is mixed with hydrogen and cracked over a catalyst (6), the product is separated into vapour and liquid in a hot separator (8); the vapour from 8 is mixed with the second feed, e.g. a wax distillate, and cracked over a catalyst (12), this product is separated into vapour and liquid in a cold separator (17); part or all of the vapour from 17 is recycled as a part of the hydrogen feed to 6; the liquid from 8 is separated into liquid and vapour at a reduced pressure, e.g. in a hot flash 11, the liquid from the hot flash is further separated, into a first lubricating base stock (21) and a vapour, e.g. in a fractionating column 20; the vapour phases from the fractionator and the hot flash and the liquid phase from the cold separator are combined and separated into vapour and liquid at reduced pressure, e.g. in a cold flash 23, and the liquid from the cold flash is further separated, e.g. in a fractionating column 26, to obtain a second lubricating base stock (27). In a modification (Fig. 2, not shown), a hot separator (181) is interposed between the second reactor and the cold separator, and it is the vapour from this hot separator that goes to the cold separator; the liquid from this hot separator is separated into liquid and vapour in a hot flash (241), and the vapour from 241 is mixed with the vapour from the first hot flash and the liquid from the cold separator and separated in a cold flash (221); the liquids from 221 and 241 and the overhead distillate from the bright-stock fractionator are combined and separated in a fractionating column (33), and the bottoms from this column are combined with a sidestream from the bright-stock fractionator to provide the second lubricating base stock. The second cracking zone may be operated under less severe conditions, that is a lower temperature or a higher space velocity, than the first. Part of the heaviest material from the first hydrocracking zone may be recycled. The catalysts in the two cracking zones may be the same or different and may contain a transition metal of Group VI or Group VIII, compounded with a porous carrier material, e.g. alumina, silica, titania, zirconia, magnesia, alumina-silica, silicamagnesia, alumina - silica - boron phosphate, silica-zirconia, mo