OXIDATIVE DESULFURIZATION OF DIESEL USING HYDROGEN PEROXIDE AND TERT-BUTYL HYDROPEROXIDE AS OXIDANTS

Oxidative desulfurization of hydrodesulfurized (HDS) diesel, HDS diesel doped with dibenzothiophene (DBT) and isooctane doped with DBT was studied by using hydrogen peroxide, tert-butyl hydroperoxide as oxidants, metal acetylacetonates like vanadyl acetylacetonate, manganese acetylacetonate, molybdenum acetylacetonate, iron acetylacetonate and, sodium tungstate as catalysts for oxidation of sulfur compounds to sulfones/sulfoxides followed solvent extraction with acetonitrile or N-methyl pyrrolidinone (NMP). Among the various catalysts studied vanadyl acetylacetonate was found to be the most effective with both hydrogen peroxide and tert-butyl hydroperoxide oxidants and yielded maximum 77.65% oxidative desulfurization of the HDS diesel with 540 ppmw initial sulfur content. The oxidative desulfurization of HDS diesel (initial sulfur content 300ppmw) doped with DBT and isooctane doped with DBT to bring their sulfur contents to 2800 ppmw, using hydrogen peroxide, vanadyl acetylacetonate oxidant system and acetonitrile as solvent for extraction yielded diesel with 262ppmw and isooctane with 40 ppmw sulfur contents. These results indicated that while it is easier to oxidize and remove DBT sulfur, it is relatively difficult to oxidize and remove sulfur compounds like 4,6-dimethyl dibenzothiophene and other similar hindered alkyl dibenzothiophene derivatives present in diesel using this oxidative desulfurization system