GB489544A - Improvements in art of refining hydrocarbons - Google Patents

Abstract

<PICT:0489544/III/1> A method of desulphurizing and sweetening light hydrocarbon oils without liberating substantial amounts of gaseous hydrogen sulphide and without substantially reducing the octane number, comprises treating the oil with hydrogen, under non-cracking conditions, in the presence of a contact material which is a metallic nickel, cobalt, copper or iron hydrogenation catalyst capable of absorbing sulphur present in the oil but which is already poisoned with such an amount of sulphur that its hydrogenating activity is insufficient to cause any substantial reduction of the octane number of the oil. The contact material, which is suitably between 1 and 25 per cent by weight of the hydrocarbon treated, may contain a mixture of the above metals, may be mixed with promoters such as alumina, chromium oxide, magnesia or thoria, and may be deposited on an inert carrier. Small amounts of alkaline compounds such as potassium carbonate or waterglass may be added. The amount of hydrogen employed is about 0,25 per cent by weight of the hydrocarbon treated, and it may be admixed with steam. The oil may be treated in the form of vapour, and temperatures of 500-900 DEG F. are employed. Treatment may take place in a number of zones, the state of activity of the contact material in the various zones being progressively higher in the direction of flow of the hydrocarbon. When the contactor is exhausted, it may be regenerated, but only to the partially poisoned condition indicated above. Apparatus for carrying out the process is shown, in which gasoline from a pipe 1, hydrogen from a tank 6, and water from a pipe 3a, are forced through a vaporizing coil 4, through a contact chamber 10, and then through a second contact chamber 11, which is at a lower temperature, but which contains contactor which is more active than that in the chamber 10. The heated mixture passes into a fractionator 35, the overhead product of which flows through a condenser 40, into a reflux accumulator 42, and may be withdrawn at 52, gaseous hydrogen in the accumulator 42 passing through a scrubber 48 to the tank 6, for re-use. As shown, the chamber is temporarily cut out of the system, and the contactor therein may be regenerated to the defined degree of activity by feeding hot air, or steam, or a mixture thereof through the pipe 58, for sufficient time to regenerate the sulphide to oxide, to the necessary degree, and then supplying hydrogen to reduce the oxide to the metallic state, the regenerated contactor, however, still remaining partly sulphur-poisoned. By suitable manipulation of the various valves, the gasoline vapours may be passed through any two of the chambers 10, 11, 12, the third chamber being used for regeneration and activation of its contactor material. According to the Specification as open to inspection under Sect. 91, metallic molybdenum, and the oxides of nickel, cobalt, copper, iron and molybdenum, are included amongst suitable desulphurizing contactors, but this subject-matter does not appear in the Specification as accepted.