Patent GB-663038-A (GB)
Title: Improvements relating to the catalytic desulphurisation of petroleum distillates
IPC: C10G45/24
Filed: 1947-12-16
Abstract: Straight - run naphthene - containing petroleum distillate, consisting of material boiling within the gas oil range and material boiling within the naphtha-kerosine range, is desulphurized by passing the distillate in vapour phase over a catalyst, which combines activity for the dehydrogenation of naphthenes to aromatics with activity for the conversion of organically combined sulphur into hydrogen sulphide and which is not poisoned as a catalyst by the presence of sulphur, at a temperature and pressure such that the dehydrogenation of naphthenes contained in the distillate is effected to an extent not substantially in excess of that required to produce sufficient hydrogen to convert organically combined sulphur contained in the distillate into hydrogen sulphide and to maintain the vapour phase in the reaction zone, overall consumption of hydrogen being avoided by separating a hydrogen-rich gas mixture and hydrogen sulphide from the treated distillate and recyling the hydrogen-rich gas mixture to the reaction zone.  The desulphurized distillate is fractionated for the separate recovery of material boiling within the gas-oil range and of material boiling within the naphtha-kerosine range.  Catalysts mentioned are one or more metal sulphides or oxides or chemical combinations of metal sulphides or oxides, for example chromium oxide, tungsten sulphide, mixture of tungsten sulphide and nickel sulphide, cobalt molybdate and cobalt thiomolybdate.  The catalysts may be mixed with, or deposited on, a porous support such as natural or heat-treated bauxite, activated alumina or kieselguhr. Natural or heat-treated bauxite may itself be used as catalyst. Preferred catalysts are cobalt molybdate supported on alumina and a pelleted mixture of cobalt oxide, molybdic oxide, alumina and graphite. In the examples: (1) a mixture of kerosine and gas-oil is passed at 780 DEG  F. and 100 lbs./sq. inch over cobalt molybdate-alumina gel catalyst with recycle of the gas formed; the treated mixture, after flashing off hydrogen sulphide and light hydrocarbons, is separated into kerosine (of increased aromatic content) and gas oil (of improved Diesel index) fractions; (2) a petroleum distillate boiling in the range 100-300 DEG  C. and comprising the heavy naphtha, kerosine and gas oil fractions is passed at 780 DEG  F. and 110 lbs./sq. inch over the catalyst of (1) with recycle of the gas formed; the treated distillate after flashing off hydrogen sulphide and light hydrocarbons, is separated into fractions boiling up to 180 DEG  C., between 180 DEG  and 250 DEG C., and above 250 DEG  C.ALSO:Straight-run naphthene-containing petroleum distillate, consisting of material boiling within the gas oil range and material boiling within the naphtha/kerosine range, is desulphurised by passing the distillate in vapour phase over a catalyst, which combines activity for the dehydrogenation of naphthenes to aromatics with activity for the conversion of organically combined sulphur into hydrogen sulphide and which is not poisoned as a catalyst by the presence of sulphur, at a temperature and pressure such that the dehydrogenation of naphthenes contained in the distillate is effected to an extent not substantially in excess of that required to produce sufficient hydrogen to convert organically combined sulphur contained in the distillate into hydrogen sulphide and to maintain the vapour phase in the reaction zone, overall consumption of hydrogen being avoided by separating a hydrogen-rich gas mixture and hydrogen sulphide from the treated distillate and recycling the hydrogen-rich gas mixture to the reaction zone.  The desulphurised distillate is fractionated for the separate recovery of material boiling within the gas oil range and of material boiling within the naphtha/kerosine range.  Catalysts mentioned are one or more metal sulphides or oxides, or chemical combinations of metal sulphides or oxides, for example, chromium oxide, tungsten sulphide, mixture of tungsten sulphide and nickel sulphide, cobalt molybdate and cobalt thiomolybdate.  The catalysts may be mixed with, or deposited on, a porous support such as natural or heat-treated bauxite, activated alumina, or kieselguhr.  Natural or heat-treated bauxite may itself be used as a catalyst.  Preferred catalysts are cobalt molybdate supported on alumina and a pelletted mixture of cobalt oxide, molybdic oxide, alumina and graphite. Hydrogen sulphide or light hydrocarbons may be removed from the hydrogen-rich gas mixture before recycle. In the examples, (1) a mixture of kerosine and gas oil is passed in vapour form at 780 DEG F. and 100lbs./sq. inch over a cobalt molybdate-alumina gel catalyst with recycle of the gas formed; the treated mixture, after flashing off hydrogen sulphide and light hydrocarbons, is separated by distillation into kerosine and gas oil fractions, (2) a petroleum distillate boiling in the range 100-300 DEG C. and comprising the heavy naphtha, kerosine and gas oil fractions is passed in vapour form at 780 DEG F. and 110lbs./sq. inch over the catalyst of (1) with recycle of the gas formed; the treated distillate, after flashing off hydrogen sulphide and light hydrocarbons, is separated into fractions boiling up to 180 DEG C. between 180 and 250 DEG C. and above 250 DEG C.