GB765004A - Conversion of hydrocarbons - Google Patents

Abstract

A catalytic cracking process comprises cracking a virgin hydrocarbon oil feed in the presence of a cracking cataylst under conditions such that less than 50 per cent by weight of the feed is cracked on a once through basis, fractionating the vaporous cracked products to obtain a cycle oil whose boiling range lies within the 10 and 80 per cent distillation points of the virgin feed and recycling the cycle oil to the cracking step, the amount of cycle oil recycled being between: <FORM:0765004/III/1> and <FORM:0765004/III/2> where A represents the weight per cent of carbon in the aromatic hydrocarbons in the virgin hydrocarbon oil feed and where B represents the volume per cent of the virgin hydrocarbon oil feed which boils within the boiling range of the cycle oil being recycled. The catalyst is preferably a silica alumina catalyst but silicamagnesia or acid treated bentonite clays may be used. The particles may be between 20 and 100 microns, and the fixed bed or moving bed processes may be used. In an example a mixed sweet gas oil having a boiling point of 600-1050 DEG F. was treated to give a product containing about 60 per cent of motor gasoline.