GB762151A - Improvements in or relating to process of sweetening sour hydrocarbon oils - Google Patents

Abstract

A doctor sweetening process comprises contacting a hydrocarbon oil with doctor solution, in the presence of free sulphur in an amount in excess of the theoretical amount needed to convert mercaptans in the oil to disulphides, and free oxygen in an amount sufficient to oxidize the PbS formed in the sweetening reaction, at a temperature of 140-200 DEG F. The process is continued until all the PbS has been converted to soluble plumbite, and doctor-sweet oil is then separated from the solution. The oxygen may be present as free oxygen or air or as a compound, such as hydrogen peroxide or potassium permanganate, which readily dissociates to produce free oxygen. The sulphur may be added as a solution in xylene. The doctor solution may contain 5-30 wt. per cent of free alkali metal hydroxide and 1.5-2.5 per cent PbO based on the aqueous alkali solution. The oil may first be washed with aqueous caustic alkali solution to remove H2.S. The sweet oil may be washed with water or passed through a coalescer, e.g. filter-paper, glass wool, crushed rock or sand. Distillates boiling below 750 DEG F., e.g. naphtha, kerosene, diesel oil, heater oil and gas oil, and distillates obtained from thermal and catalytic cracking and reforming processes, may be treated.