Abstract: The oxidation processes, oxidation products and colors of nitrogen-containing compounds and sulfur-containing compounds were studied using a density functional theory based on quantum mechanical method, and the effects of nitrogen-containing compounds and sulfur-containing compounds on the oxidation stability of base oil were investigated by model compound test. The results show that the oxidation of nitrogen-containing compounds to carbonyl compounds can promote the oxidation of other organic hydrocarbon molecules, and carbonyl was the chromogenic group of the oxidizing products.The sulfur-containing compounds were oxidized to sulfoxide compounds containing sulfinyl or sulfone compounds containing sulfuryl, which did not produce new hydroperoxide radicals and could stop the oxidation reaction of free radicals. The sulfur-containing compounds did not show color.

Key words: lube base oil, adsorption refining, nitrogen-containing compound, sulfur-containing compound, oxidation stability