Sustainable Green Fuel Technology via Photocatalytic Desulfurization of Dibenzothiophene Under Visible Light Using Mixed Nanocomposite Catalyst

Abstract

The growing desire for clean fuels and the severe standards for sulfur emissions have spurred the development of efficient and sustainable desulfurization processes. In the present work, a visible-light-driven mixed nanocomposite (CuO@TiO2) was prepared and tested as a photocatalyst for the photo-degradation of dibenzothiophene (DBT), which is deleterious to the environment and the major sulfur-containing component of fossil fuels. The composite was synthesized by a facile process and characterized by XRD, FT-IR, Raman, BET measurements, SEM, EDX, UV–Vis diffuse reflectance spectroscopy (DRS), and PL. The visible-light-driven photocatalytic activity of mixed composite was higher than that of TiO₂ and CuO alone, due to the enhanced charge separation, the narrowed bandgap and the strong interaction between CuO and TiO₂ under visible-light irradiation. The photodegradation activity was markedly affected by the amount of catalyst, addition of oxidizing agent (hydrogen peroxide, H2O2) and irradiation time. A proposed mechanism indicated that superoxide and hydroxyl radicals were primarily responsible for DBT oxidation. The DBT removal under the optimum condition was 99.67%, while the real sample of diesel feedstock (1300ppm-Sulfur content) was 95.37% under LHL light and under Sun light was 98.92%. An extraction step was involved in the case of using real sample of diesel fuel to remove the oxidized sulfur compounds by using acetonitrile as solvent. Moreover, the catalyst showed high stability and reusability for six cycles, and could be a promising candidate to actual fuel desulfurization. This work provides a green, efficient and low-cost approach for the preparation of ultra-low sulfur fuel based on solar energy.