GB1337494A - Combination process for treatment of hydrocarbon streams containing a mercapto compound - Google Patents

Abstract

1337494 Desulphurizing and sweetening hydrocarbons UNIVERSAL OIL PRODUCTS CO 31 March 1971 8311/71 Heading C5E A liquid stream of relatively low boiling hydrocarbon 1 containing mercapto compounds is contacted at 2 with an alkaline stream 6 to produce an alkaline extract stream 7 and a product hydrocarbon stream 3 from which it is separated into a hydrocarbon stream 5 which is substantially free of sulphur compounds and an alkaline stream 6. A liquid stream of relatively high boiling hydrocarbon 25 containing mercapto compounds is contacted at 16 with an alkaline stream 15 to produce an alkaline extract stream 17 and a stream 18 containing hydrocarbons. The stream 18 is contacted with air 27 and a catalyst in the sweetening zone 19 and then separated at 21 into a gas 22 containing nitrogen, a hydrocarbon stream 26 containing disulphide compounds but which is substantially free from mercapto compounds, and an alkaline stream 23 which is substantially free of mercapto and disulphide compounds. At least a portion of the stream 23 is recycled to the extraction zone 2 and the remainder can be recycled to the sweetening zone 19. The alkaline extracts 7 and 17 are contacted with air 8 and a catalyst in the regeneration zone 9 and the effluent 10 separated into a gas 12 containing nitrogen, a stream 13 containing disulphide compounds and an alkaline stream 14 containing disulphide compounds. The stream 14 is in part recycled to the extraction zone 16 as the stream 15 and in part passed to the sweetening zone 19. The catalysts used in the zones 9 and 19 can be a metal, e.g. cobalt, vanadium, iron, copper, nickel or chromium, phthalocyanine which can be used as the mono-, di-, tri- or tetra-sulphonate. This catalyst can be used as an aqueous solution or dispersion or as a fixed bed on a carrier such as activated charcoal. The separating zones 4 and 11 can contain steel wool, sand or glass to assist the separation of the hydrocarbon/alkaline solution dispersion. The alkaline solution can be an aqueous solution of sodium or potassium hydroxide, e.g. 1-50 wt. per cent aqueous sodium hydroxide, and can also contain alcohols, alkylphenols or dialkylsulphoxides to increase the solubility of mercapto compounds. The feed 1 can contain C 3 and/or C 4 hydrocarbons and the feed 25 can be a cracked gasoline, a straight-run gasoline, a naphtha, a jet fuel or a kerosene; these feed streams can be first washed with dilute sodium hydroxide to remove hydrogen sulphide.