Petroleum deodorized: Early canadian history of the ‘doctor sweetening’ process

Summary

During a period of about four decades following World War I, gasoline was often deodorized at refineries by treatment with alkaline solutions of lead oxide, a procedure generally denoted ‘doctor sweetening’. Contemporary accounts describe it as old, but are generally vague about its origin. This paper traces the early history of the treatment of petroleum distillate by alkaline plumbite solution, dating back to 1866 when it was introduced in Germany by Rudolf Wagner. After 1869, this procedure became the preferred method for deodorizing Canadian kerosene and other petroleum products which were afflicted by unusually high sulphur content. Subsequently, Hermann Frasch improved on this method by distilling the afflicted petroleum in the presence of solid metal oxides.