Oxidative desulfurization of diesel fuels by molecular oxygen

The co-oxidation of aldehydes and S-containing compounds, e.g., dibenzothiophene, was studied by molecular oxygen to develop a new system for deep desulfurization of petroleum-derived fuels. Several metal salts and aldehydes were examined as catalysts. Both Co(II) acetate and chloride were the most suitable catalysts among the metal salts employed and aliphatic aldehydes with 6-10 carbons and benzaldehyde could be used. The desulfurization of commercial diesel oil was tried using this method. The commercial oil was treated with cobalt acetate and n-octanal at 40°C for 16 hr under oxygen. Oxidized S-compounds were removed from the feed by adsorption with alumina. Concentration of sulfur could be reduced from 193 wt ppm (in the original feed) to < 5 wt ppm by these treatments. This new oxidative desulfurization process has a potential to meet a future regulation of sulfur in the diesel fuel.