GB782942A - Process for reduction of the hydrogen sulphide and mercaptan sulphur content of aqueous caustic alkali liquors - Google Patents

Abstract

Aqueous caustic alkali solution which has been used for removing hydrogen sulphide and/or mercaptans from hydrocarbons is regenerated by treatment with oxygen, e.g. in the form of air, in the presence of a compound of manganese or nickel, produced by the addition of a salt or hydroxide of manganese or nickel to the liquor, and an absorbent consisting of active carbon, coal coke, lignite coke, petroleum coke, finely-divided ash from coal or lignite, "Bayer mass" or an iron oxide as such or in the form of an ore, e.g. bog iron ore. Bayer mass is a residue of iron oxide or hydroxide obtained in the preparation of alumina from bauxite. The manganese or nickel salt or hydroxide may be admixed with the absorbent and the mixture added to the liquor, or the manganese or nickel salt or hydroxide may be separately added to the liquor. The temperature of reaction may be 10-90 DEG C. and the time of reaction 10-48 hr. The combined quantity of the metal salt or hydroxide and absorbent used may be 0.1-20, preferably 5, gm./100 c.c. of liquor and the proportion of metal salt or hydroxide is the combined quantity of the metal salt or hydroxide and absorbent may be 0.01-10, preferably 0.05-5, per cent. Spent caustic soda solution having a concentration of e.g. 150-200 gm./l. may be used. The oxygen may be passed through waste caustic alkali liquor before the oxidation step. The oxygen may be passed into the liquor to be regenerated as fine bubbles, e.g. by way of a jet or frit. Specification 499,709 is referred to.