SYNTHESIS AND CHARACTERIZATION OF V/SIO2 CATALYSTS FOR CATALYTIC OXIDATIVE DESULFURIZATION OF DIBENZOTHIOPHENE USING HYDROGEN PEROXIDE

In the present study, vanadium-supported silica (V/SiO₂) catalysts with different nominal vanadium loadings (1, 3, and 5 wt%) were prepared by a two-step procedure involving sol–gel synthesis of the silica support followed by impregnation with ammonium metavanadate (NH₄VO₃). The prepared materials were characterized by Fourier-transform infrared (FT-IR) spectroscopy and N₂ adsorption–desorption analysis. The FT-IR spectrum of V/SiO₂ exhibited characteristic absorption bands at approximately 1095 and 798 cm⁻¹, corresponding to vibrational modes of the Si–O–Si framework, together with a band at approximately 948 cm⁻¹ associated with vanadyl/vanadium oxide species on the silica surface. The bare SiO₂ exhibited a BET surface area of 340 m² g⁻¹, a total pore volume of 0.51 cm³ g⁻¹, and an average pore diameter of 6.8 nm. With increasing vanadium loading, the BET surface area decreased to 328, 230, and 226 m² g⁻¹ for the 1, 3, and 5 wt% V–SiO₂ catalysts, respectively, while the pore volumes decreased to 0.49, 0.43, and 0.42 cm³ g⁻¹. The corresponding average pore diameters were 6.3, 5.8, and 5.8 nm, respectively. The catalytic performance of the prepared catalysts was evaluated for the oxidative removal of dibenzothiophene (DBT) from a model fuel using H₂O₂ as the oxidizing agent. Among the investigated catalysts, 3 wt% V–SiO₂ exhibited the highest catalytic activity. Under the optimum conditions of 60 °C, 60 min, 0.2 g catalyst, and an H₂O₂/DBT molar ratio of 6, a maximum DBT removal of 94.8% was achieved. The optimum catalyst retained 79.4% of its initial activity after four consecutive reaction cycles, indicating good stability and reusability. These results demonstrate the potential of V/SiO₂ as an effective heterogeneous catalyst for the oxidative removal of refractory sulfur compounds from model fuels under relatively mild conditions.