GB428931A - Improvements in and relating to the purification of hydrocarbons - Google Patents

Abstract

Benzol, which may have been treated with 77 per cent sulphuric acid, water, and aqueous alkali, is freed from carbon disulphide and other sulphur compounds by vigorously agitating with a mixture of methyl alcohol and at least 1,5 lb. of solid caustic alkali per gallon of alcohol, separating the agent, and washing with water. 2--5 per cent of methyl alcohol is suitable. Methyl alcohol and carbon disulphide or alkali methyl xanthate are recovered from the used agent by: (a) adding carbon disulphide to react with all remaining alkali and distilling under reduced pressure whereby methanol distils over and xanthate remains as a pale yellow hydroscopic solid; or (b) diluting with water before or after separation of the benzol, separating the benzol, acidifying e.g. with sulphur dioxide or 20--30 per cent sulphuric acid, and separating the disulphide e.g. by collecting the first fractions under water collecting, as described in Specification 416,404; or (c) diluting with 0,5-1,0 vol. of water after separation of the benzol, distilling, and fractioning the mixture obtained. The disulphide may be refined by washing with 5--10 per cent caustic soda, water, 77--95 per cent sulphuric acid, water, and dilute alkali or soda ash, and fractionally distilling. In an example, 20 gallons of anhydrous methanol, 50 lb. of flake caustic soda, and 2500 gallons of benzol are agitated together for 3 hrs. In a second example the methanol contained 10 per cent of water. Specifications 15777/12, [Class 1 (ii)], and 335,952, [Class 91], also are referred to.