GB411477A - Improvements in the manufacture and production of liquid hydrocarbons of low boiling point by the thermal treatment of tars, mineral oils and the like - Google Patents

Abstract

In a process for cracking hydrocarbon oils of the kind in which the oil in the presence of a finely divided catalyst is flowed continuously through a preheater and a reaction chamber heated to 400--600 DEG C, part of the catalyst is added, preferably in batches, to the oil after it has been heated to reaction temperature at several successive places following each other in the direction of the flow of the oil, and the vapours formed and the liquid reaction products containing catalysts suspended therein are removed continuously from the reaction vessel. The metals or their compounds of Groups 2--8 of the periodic system may be used as catalysts advantageous compounds being oxides, halides or acid salts, and active silica, carbon, kieselguhr, coke, &c., may be impregnated with the catalytic substances. Catalysts also may be used which decompose during the reaction, e.g. carbonyls, oxalates, or organic halogen compounds. The catalyst may be supplied to the reaction vessel by tubes of different lengths, made into a paste with oil free from asphalt, and may be added at places having different temperatures or different catalysts may be added at different places. Pressures up to 100 atmospheres or over may be used or atmospheric pressure in which case hydrogen may be present. An oil fraction boiling above 325 DEG C. is heated to 485 DEG C. in a gas heated tube system the pressure rising to 50 atmospheres. As soon as the oil has reached a temperature of 420 DEG C. 0,5 per cent by weight of the oil of a catalyst consisting of active carbon impregnated with zinc chloride is added at different places in the tube system and when the oil has attained 485 DEG C. a further 0,5 per cent of catalyst is added and the oil passed into a cracking chamber of greater cross section. A yield of 45 per cent benzine is obtained.