Desulfurization and denitrogenation process for light oils based on chemical oxidation followed by liquid-liquid extraction

A desulfurization and denitrogenation process for light oils has been investigated based on the chemical oxidation of sulfur-and nitrogen-containing compounds using hydrogen peroxide and acetic acid as oxidizing agent. Sulfur and nitrogen compounds, when dissolved in n-tetradecane and xylene, were oxidized under moderate conditions and were removed successfully. By use of this basic process, although nitrogen content of actual light oils was reduced to <22% of the corresponding feed values, sulfur content failed to be reduced to the required deep desulfurization level (0.05 wt %). This is because the alkyl-substituted sulfones, produced during the oxidation of sulfur compounds, remain in the resulting light oils, owing to their high hydrophobicity. These, however, may be removed from the light oils by subsequent extraction, using an acetonitrile/ water azeotropic mixture, such that the sulfur contents of the light oils were decreased to <0.05 wt %, while maintaining a high oil recovery yield.