GB669536A - Improvements relating to the catalytic desulphurisation of kerosine and white spirits - Google Patents

Abstract

A kerosene or white spirits fraction of petroleum is desulphurized by passing 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 <PICT:0669536/III/1> organically combined sulphur to hydrogen sulphide and which is not poisoned as a catalyst by the presence of sulphur compounds, at a temperature and pressure such that the dehydrogenation of naphthenes present 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 into hydrogen sulphide and to supply the hydrogen for recycling to the reaction zone to maintain the vapour phase therein. The temperature used is preferably 700 DEG -800 DEG F and the pressure 50-250 p.s.i. The recycle rate of the hydrogen may be 4,000-6,000 cu. ft./bbl. of feedstock. Metal sulphides and oxides, especially those of the 6th group may be used as catalysts, for example chromium oxide, tungsten sulphide, tungsten sulphide and nickel sulphide, and cobalt molybdate or thiomolybdate, and may be mixed with, or deposited on, a porous support such as natural or processed bauxite, activated alumina and kieselguhr. A pelleted catalyst may be prepared by mixing powdered cobalt oxide, molybdic oxide and alumina, and pelleting with 1 per cent graphite into 3/16th inch pellets which are treated for two hours at 550 DEG C. Alternatively the catalyst may be prepared by extrusion. As shown, an unrefined Iranian kerosene is fed via line 11, heat exchanger 12 and preheater 13 to a reactor 10 charged with cobalt molybdate on alumina. The products are cooled in cooler 14 and passed to gas separator 15. The gases separated are recycled to the reaction zone through line 16 at a rate of 4,000 cu. ft./bbl. and the liquid product containing the hydrogen sulphide in solution depressurized in separator 19 from which the hydrogen sulphide is removed via line 20. Specifications 654,152 and 669,553 are referred to.