GB682317A - Improvements relating to the catalytic cracking of petroleum hydrocarbons - Google Patents

Abstract

Petroleum hydrocarbons are desulphurized by passing them in vapour form in admixture with hydrogen over a catalyst which combines activity for dehydrogenation of naphthenes to aromatics with activity for the conversion of organically combined sulphur to hydrogen sulphide, at a temperature and pressure such that the dehydrogenation of naphthenes contained in the fraction is effected to an extent not substantially in excess of that required to produce sufficient hydrogen to convert the organically combined sulphur as the fraction into hydrogen sulphide and to maintain the vapour phase in the reaction zone, a hydrogen-rich gas mixture being separated from the treated fraction and recycled to the desulphurization zone The desulphurized fraction is then passed to a catalytic cracking zone. As catalysts there may be used metal sulphides and oxides, especially those of the sixth group, for example chromium oxide, tungsten sulphide, nickel sulphide and cobalt molybdate or thiomolybdate, and the catalyst may be deposited on a carrier such as natural or heat-treated bauxite, activated alumina or kieselguhr. The preferred catalyst is cobalt molybdate supported on alumina. The desulphurizing reaction is preferably carried out at a temperature of 650 DEG -800 DEG F and at a pressure of 25-500 lbs./sq. in. Specifications 654,152, 663,038, 669,536, 669,552 and 679,175 are referred to.