GB918302A - Catalytic conversion of aromatic distillates - Google Patents

Abstract

High octane gasoline is produced by isocracking a hydrocarbon fraction having an aromatic content of at least 30% by volume, a basic nitrogen content of less than 25 p.p.m. and a 10-90% boiling range within the range 330 DEG -650 DEG F. in the presence of at least 2,000 SCF of hydrogen per barrel of feed and a catalyst having a hydrogenating component disposed on an active cracking support and having a severity factor of 0,1-2,0 at an average catalyst temperature of 300 DEG -750 DEG F. and at least 400 p.s.i.g. The severity factor is defined as the ratio of volume per cent aromatics in the feed to that in the product minus 1 when employing a trimethylbenzene concentrate under standard conditions of 650 DEG F., 1200 p.s.i.g., 9,000 SCF hydrogen per barrel of feed and a LHSV of 2. Suitable supports are silica-aluminas containing 75-95% silica, e.g. one having a cat A activity of 46 and a surface area of 430 M2/g. The support may contain 0,1-30% of a group IB, IIB, VI or VIII metal or oxide or sulphide thereof, nickel sulphide being preferred. The feed may be a naphtha, kerosene, gas oil or cycle oil of straight run origin or obtained by thermal or catalytic cracking of stocks obtained from petroleum, gilsonite, shale or coal tar, or a reformed fraction. Nitrogen content may be reduced by hydrofining if necessary. The feed is introduced as vapour and/or liquid according to conditions at a LHSV of 0,2-5. The conversion is preferably maintained at a steady value of 20-70% and the hydrogen consumption at 1,000-2,000 SCF per barrel of converted feed. Product boiling above 330 DEG may be recycled to extinction.