Patent GB-603808-A (GB)
Title: The catalytic treatment of sulfur-bearing hydrocarbon distillates
IPC: C10G45/04
Filed: 1945-10-30
Abstract: Cracked or reformed gasolines and similar olefinic hydrocarbon distillates containing more than 0.1 per cent sulphur are treated to increase the aromatic content, decrease the amount of olefins and desulphurize with a sulphide of a metal of the iron group at about 850-910 DEG  F. and at least 20 atm. in the presence of about 1-30 volumes of hydrogen, the sulphur concentration in the hydrocarbon feed to the reaction zone being maintained below 0.1 per cent.  This may be effected by treatment with a sulph-active hydrogenation catalyst below 850 DEG , preferably 500-810 DEG  F., and above about 10 atm. in presence of 1-30 volume of hydrogen, and with a liquid hourly space velocity of about 4-30.  Thus, a 300 DEG  F. end-point fraction obtained by cracking a high sulphur petroleum with a clay catalyst, and containing 0.18-0.52 per cent sulphur is mixed with recycled hydrogen and passed over a catalyst comprising metal of Groups 5, 6 or 7, the iron group, zinc or copper or their sulphides or oxides, e.g. cobalt thiomolybdate-alumina, tungsten-nickel or tungsten-iron sulphides, nickel sulphide-alumina, molybdenum oxide-zinc oxide-magnesia, molybdenum oxide-chromium oxide-alumina and nickel-copper-alumina, to reduce the sulphur to 0.08 per cent. Hydrogen is recycled after removal of H2S.  The olefinic product is then treated with an iron group metal sulphide, e.g. cobalt or nickel thiomolybdate, nickel sulphide, or nickel-tungsten-sulphides under the conditions specified.  Alternatively, sulphur is maintained below 0.1 per cent by recycling part of the product. Thus, a thermally cracked and reformed gasoline containing .16 per cent sulphur is fed with recycled product containing .005 per cent sulphur and hydrogen over the iron group sulphide catalyst, e.g. cobalt or nickel with tungsten or molybdenum sulphides.  The feed may also be diluted with a sulphur-free olefin polymer or straight run gasoline in the case of either the two or single step methods described.  In some cases the feed may be separated by extractive distillation into a high and low sulphur fraction, the former being treated by the two-step method and the latter recombined therewith prior to the second step.  Mercaptans may first be removed from the feed by selective extraction, by oxidation to disulphides or by passage over bauxite, active clay or a metal oxide which decomposes them.  By limiting the first step treatment to reduce sulphur only to just below 0.1 per cent, the olefins are substantially unchanged and are hydrogenated in the second step whereby heat is supplied for the endothermic dehydrogenation.  Examples illustrate the improvement in catalyst life by decreasing the sulphur content of cracked gasoline feeds.ALSO:Cracked or reformed gasolines and similar olefinic hydrocarbon distillates containing more than 0.1 per cent sulphur are treated to increase the aromatic content, decrease the amount of olefins, and desulphurize with a sulphide of a metal of the iron group at about 850-910 DEG  F. and at least 20 atm. in the presence of about 1-30 volumes of hydrogen, the sulphur concentration in the hydrocarbon feed to the reaction zone being maintained below 0.1 per cent.  This may be effected by treatment with a sulph-active hydrogenation catalyst below 850 DEG , preferably 500-810 DEG  F., and above about 10 atm., in presence of 1-30 volumes of hydrogen and with a liquid hourly space velocity of about 4-30.  Thus, a 300 DEG F. endpoint fraction obtained by cracking a high sulphur petroleum with a clay catalyst, and containing 0.18-0.52 per cent sulphur is mixed with recycled hydrogen and passed over a catalyst comprising metals of Groups 5, 6 or 7, the iron group, zinc or copper or their sulphides or oxides, e.g. cobalt thiomolybdate-alumina, tungsten-nickel or tungsten-iron sulphides, nickel sulphide-alumina, molybdenum oxide-zinc oxide-magnesia, molybdenum oxide-chromium oxide-alumina, and nickel-copper-alumina, to reduce the sulphur to 0.08 per cent. Hydrogen is recycled after removal of H2S.  The olefinic product is then treated with an iron group metal sulphide, e.g. cobalt or nickel thiomolybdate, nickel sulphide or nickel-tungsten sulphides under the conditions specified. Alternatively, sulphur is maintained below 0.1 per cent by recycling part of the product.  Thus, a thermally cracked and reformed gasoline containing .16 per cent sulphur is fed with recycled product containing .005 per cent sulphur and hydrogen over the iron group sulphide catalyst, e.g. cobalt or nickel with tungsten or molybdenum sulphides.  The feed may also be diluted with a sulphur-free olefin polymer or straight-run gasoline in the case of either the two or single-step methods described.  In some cases, the feed may be separated by extractive distillation into a high and low sulphur fraction, the former being treated by the two-step method and the latter recombined therewith prior to the second step.  Mercaptans may first be removed from the feed by selective extraction, by oxidation to disulphides or by passage over bauxite, active clay or a metal oxide which decomposes them. By limiting the first step treatment to reduce sulphur only to just below 0.1 per cent, the olefins are substantially unchanged and are hydrogenated in the second step whereby heat is supplied for the endothermic dehydrogenation. Examples illustrate the improvement in catalyst life by decreasing the sulphur content of cracked gasoline feeds.