Prepartion of phosphotungstic acid functionalized carbon nitride and its catalytic performance in oxidative desulfurization of model oil

A new phosphotungstic acid functionalized carbon nitride (g-C₃N₄/HPW) was prepared with carbon nitride and phosphotungstic acid as raw materials. The structure of g-C₃N₄/HPW was characterized by XRD, FT-IR and SEM; with g-C₃N₄/HPW as a catalyst, the oxidative desulfurization of model oil containing dibenzothiophene (DBT) was carried out by using hydrogen peroxide as oxidant and imidazolium tetrafluoroborate ionic liquid as extractant. The influences of reaction temperature, catalyst amount, extractant amount, H₂O₂ amount, type of thiophene on the desulfurization efficiency were investigated. The results indicate that under the optimal reaction conditions, viz., 5 mL model oil, 0.02 g g-C₃N₄/HPW, 1.0 mL H₂O₂, 1.5 mL BF₄, 70 ℃ and reaction time of 120 min, the desulfurization efficiency reaches 93%. Moreover, there is no significant decrease in the desulfurization activity after the catalyst system was recycled for 4 cycles.