GB745633A - Improvements in or relating to process of refining hydrocarbon distillates - Google Patents

Abstract

Mercaptons are removed from a sour hydrocarbon distillate without the formation of colour greater than about 1 N.P.A. therein by dispersing a copper compound in the distillate, intimately contacting the copper-containing distillate with about 1-15 per cent by volume of an aqueous solution of KOH having a concentration of about 50-60 per cent by weight so that the copper compound, which in amount ranges from about 0.004 to 0.1 per cent by weight of copper based on the KOH solution, forms a copper compound active as an oxidation catalyst by contact with the KOH solution, introducing an oxygen-containing gas into the mixture of catalyst-containing distillate and KOH solution, maintaining the temperature of contacting at about 80-125 DEG F. and separating spent KOH solution and associated reaction products from the treated distillate. The spent KOH solution may be allowed to settle so that potassium cresylates separate out as a distinct layer which is then removed. The spent KOH solution may then be regenerated by distillation and employed for the treatment of additional quantities of hydrocarbon distillate. The oxygen-containing gas, which may be air or oxygen, may be employed in an amount which is about 1 1/2 -2\ba1/2 times that theoretically required for converting mercaptons present in the hydrocarbon distillate to disulphides. Hydrocarbon distillates mentioned are naphtha, kerosene, heater oil and furnace oil, derived from the distillation of crude oil or from thermal or catalytic cracking processes. In the case of air, the sweetening treatment may be carried out at 25-200 p.s.i.g., but the use of increased pressure is not ordinarily necessary in the case of oxygen. The copper may be added in the form of an aqueous solution of a copper salt such as copper chloride, sulphate, nitrate or acetate so as to form a very fine dispersion in the hydrocarbon distillate, and preferably a water-in-oil emulsion. When added in this way, the copper reacts with the KOH to form a blue compound, which is believed to be colloidal copper oxide, active as an oxidation catalyst. The hydrocarbon distillate may be given a preliminary wash with an alkaline solution, e.g. sodium hydroxide or carbonate, to remove H2S, while the sweetened distillate may be passed through a fibrous or finely granular material such as glass wool, rock wool or sand, and then washed with water, in order to remove traces of KOH. A small amount of a metal deactivator such as N. N1-disalicylidene -1, 2-diaminopropane may be added to the sweetened hydrocarbon distillate. Specifications 728,057 and 745,631 are referred to.