Oxidation of dibenzothiophene catalyzed by Na2WO4 in a halogen-free ionic liquid

Deep removal of dibenzothiophene from model diesel under mild conditions (323 K) by oxidation with H2O2 was studied, using Na2WO4 center dot 2H(2)O in a halogen-free ionic liquid. The removal of DBT could reach 99.4% and the sulfur content would be reduced from initial 500 to 3 mu g/g, which can meet the standards of ultra-deep desulfurization. The model diesel after oxidation could be easily separated by simple decantation, demonstrated an effective and simple separation method. This catalytic system can be recycled five times without significant change on desulfurization results. The mechanism of the catalytic oxidation process was also proposed, a new ionic liquid-peroxytungstate complex was generated as the active species for supplying the active oxygen for desulfurization reaction.