Preparation of g-C₃N₄ supported phosphotungstate hybrid materials and their catalytic performance in the oxidative desulfurization

A series of supported Bmim₃PW₁₂O₄₀/g-C₃N₄ catalysts (BPWO/g-C₃N₄) was prepared by coprecipitation, with 1-butyl-3-methylimidazole bromide, phosphotungstic acid and g-C₃N₄ as the raw materials. The morphology and structure of the BPWO/g-C₃N₄ catalysts were characterized by XRD, FT-IR, UV-vis, N₂ physisorption, TEM and XPS; the effects of catalyst composition, oxygen to sulfur (O/S) ratio, catalyst amount and reaction temperature on the oxidative desulphurization efficiency were investigated by using n-heptane solution of dibenzothiophene (DBT) as a model oil and hydrogen peroxide as the oxidant. The results indicate that the BPWO/g-C₃N₄ catalysts have a Keggin-type heteropoly anionic structure and BPWO is well dispersed on g-C₃N₄. The BPWO(20%, mass ratio)/g-C₃N₄ catalyst exhibits the optimal oxidation performance towards DBT. Under 50℃ and with a O/S molar ratio of 6.0, DBT in the model oil with a concentration of 800 μg/g can be completely oxidized over the BPWO(20%, mass tatio)/g-C₃N₄ catalyst in 180 min. Moreover, the BPWO(20%, mass ratio)/g-C₃N₄ catalyst displays a good reusability and can be recycled for at least 8 cycles without any decrease in the DBT oxidation activity.