Oxidative Desulfurization of DBT over Vanadium-Based Catalysts

The oxidative desulfurization (ODS) process is a promising complementary process to the hydrodesulfurization (HDS) to remove refractory sulfur compounds of liquid fossil fuels such as benzothiophene (BT), dibenzothiophene (DBT), and their alkyl derivatives. Vanadium oxide has different oxidation states which may result in unique catalytic properties. In this study, the γ-alumina-supported vanadium oxide catalysts were prepared by incipient wetness impregnation and used as an oxidative desulfurization catalyst. The catalyst samples were characterized by N2 adsorption-desorption, X-Ray Diffraction (XRD), Fourier-Transform InfraRed (FT-IR) spectroscopy, and Energy-Dispersive X-ray Spectroscopy (EDS). The oxidative desulfurization was conducted at 80 °C and 1.0 atmosphere with tert-butyl hydroperoxide to DBT (O/S) molar ratio of 5.0 in the presence of 0.03 g catalyst per 3.0 g of model fuel containing 500 ppmw S (as DBT). A comparison of catalysts containing 2, 3, and 6 wt.% vanadium revealed that the best catalytic activity was achieved for 6 wt.% vanadium on the γ-alumina with 100% conversion of DBT after only 5 min of the reaction. In addition, the effect of O/S mole ratio on the desulfurization efficiency was investigated and the best result was obtained at O/S=5.