Food-grade White Mineral Oil: Naphthenic Distillate Hydrogenated in Three Stages

Food-grade white mineral oil carries only a trace of aromatics. The older way to get there was solvent extraction and sulphuric acid. Everett (Atlantic Richfield, US 5,294,327, 1994) uses hydrogen alone, in three stages, on a naphthenic distillate. Each stage cuts the aromatics further, with strippers between them to take off hydrogen sulfide and ammonia. The end product has about 0.3 % aromatics or less. The patent gives no catalyst recipe, amounts or flow rates. The stripper gases hold hydrogen sulfide, a deadly gas. The picture: the patent's drawing.