Catalytic oxidation of mercaptans and removal of naphthenic acids, catalyst toxins, and toxin precursors from petroleum distillates

A process for the catalytic oxidation of mercaptans in a sour petroleum distillate containing difficultly oxidizable mercaptans, catalyst toxins and toxin precursors which comprises:

• a. treating said distillate in contact with an alkaline solution and extracting naphthenic acids from said distillate, said alkaline solution having a pH of from about 8 to about 10;
• b. treating at least a portion of the substantially naphthenic acids-free distillate in contact with an oxidizing agent and an alkaline metal phthalocyanine solution having a pH of from about 9 to about 14, and oxidizing the residual catalyst toxins and toxin precursors contained therein, and converting a portion of the mercaptans to disulfides;
• c. passing at least a portion of the resulting reaction mixture from step b through a bed of solid adsorbent particles and adsorbing said oxidized toxins, toxin precursors, and the metal phthalocyanine solution on said adsorbent;
• d. treating at least a portion of the toxin-free and toxin precursor-free distillate from step c in contact with an alkaline solution and a supported metal phthalocyanine catalyst in the presence of an oxidizing agent, said alkaline solution having a pH of from about 9 to about 14;
• and
• e. recovering the resultant distillate from step d substantially free of mercaptans.