Synthesis BiVO4 modified by CuO supported onto bentonite for molecular oxygen photocatalytic oxidative desulfurization of fuel under visible light

A highly photocatalytic activity of bismuth vanadate (BiVO4) modified by CuO was synthesized loaded onto the bentonite (BTT) and applied to photocatalytic oxidative desulfurization of model oil. The photocatalyst was characterized by XRD, SEM, EDS, FT-IR, XPS and UV–vis DRS. The influences of the mass ratio of cata./model oil, the flow rate of molecular oxygen and the irradiation time on the photocatalytic oxidative desulfurization of model oil were investigated by using molecular oxygen as the oxidant. The sulfur removal performances and products of the photocatalytic oxidative desulfurization of benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) in model oil under visible light were also discussed. The results showed that the photocatalytic activity of CuO modified BiVO4/BTT for organic sulfur compounds under visible light was significantly higher than that of BiVO4 and BiVO4/BTT. Its oxidative desulfurization reactions for BT, DBT, 4-6DMDBT were the pseudo-first-order reaction, and the desulfurization activity as well as apparent activation energy followed the order of DBT > 4,6-DMDBT > BT. The photocatalytic oxidative desulfurization mechanism of CuO-BiVO4/BTT was analyzed through the calculated band gap, valence band and conduction band position. The recycling experiment presented that DBT removal by CuO-BiVO4/BTT still reached 81.5% after ten cycles.