Oxidative desulfurization of model oil with choline chloride/oxalic acid as a eutectic solvent

Choline chloride/oxalic acid as a eutectic solvent was synthesized by the reaction of choline chloride with oxalic acid at 100℃ via simple stirring. The removal of dibenzothiophene (DBT) in model oil was carried out by using choline chloride/oxalic acid as a catalyst, hydrogen peroxide as oxidant, imidazolium tetrafluoroborate ionic liquid as extractant; the influence of reaction temperature and time, the amount of hydrogen peroxide, the type of extractant, the type of sulfur-containing compound (thiophene and its homologues) on the desulfurization efficiency were investigated. The results indicated that under the optimal reaction conditions of n(H₂O₂)/n(S)=8, reaction temperature of 30℃ and time of 80 min, the desulfurization efficiency for DBT reaches 95%. Moreover, the reaction system can be recycled for 5 times without a significant decrease in the desulfurization activity.