Method for treating mercaptans contained in a sour petroleum distillate

A method of treating a mercaptan-containing sour petroleum distillate which comprises contacting said distillate at oxidation conditions with a catalytic composite comprising a carrier material, a metal chelate oxidation catalyst, a substituted ammonium compound, and a linear ionic compound containing from about 9 to about 24 carbon atoms and having an anionic portion, wherein said anionic portion is selected from the group consisting of sulfonate, sulfate and carboxylate, said substituted ammonium compound being represented by the structural formula:

• ##STR4## where R is a hydrocarbon radical containing up to about 20 carbon atoms and selected from the group consisting of alkyl, cycloalkyl, aryl, alkaryl and aralkyl, R.sub.1 is a substantially straight-chain alkyl radical containing from about 5 to about 20 carbon atoms, and X is an anion selected from the group consisting of halide, nitrate, nitrite, sulfate, phosphate, acetate, citrate, tartrate and hydroxide.