GB497255A - An improved process for refining petroleum distillates - Google Patents

Abstract

A process for sweetening sour mineral oil distillates consists in removing the mercaptans by (a) converting them into copper mercaptides, and (b) extracting these by a selective solvent such as an alkylamine or an alkylolamine. The oil may be previously washed with a dilute aqueous solution of alkali such as sodium carbonate solution to remove hydrogen sulphide. Sour gasoline is agitated with ammoniacal cupric sulphate solution until the mercaptans are converted to copper mercaptides. The mixture is allowed to settle till two layers are formed. The oil layer is drawn off and agitated with a 10 per cent volume of ethanolamine. On allowing to stand, the gasoline and amine layers are separated. The gasoline layer gave a negative test for mercaptans when treated with sodium plumbite solutions. After treating with copper salt solution, the gasoline may be partly distilled at a temperature below the decomposition temperature of the mercaptides, and the still bottoms then treated with alkyl amine or alkylol amine to dissolve out the mercaptides. The distillate and extracted parts are then blended. Instead of ammoniacal copper sulphate solution, a solution of the copper sulphate or other salt in the extraction agent may be used. The process may be carried out with batches or as a continuous counter current process.