Ultra-deep photocatalytic oxidative desulfurization of liquid fuels by Ti@CeO2/ZnO nanophotocatalyst under visible light and mild operating conditions

Abstract

Herein, various Ti@CeO2/ZnO nanophotocatalysts (TxCZ, x: the molar ratio of Ti to Ce and Zn) were synthesized using the solvothermal method in two stages. After that, the effectiveness of the fabricated catalysts in the photocatalytic oxidative desulfurization (PODS) reaction were assessed. The physicochemical properties of the synthesized samples were analyzed through the implementation of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS), photoluminescence spectroscopy (PL), and electron paramagnetic resonance (EPR) techniques. The study evaluated the impact of varying levels of titanium loading on the physicochemical characteristics of nanoparticles and the elimination of sulfur compounds. Under the optimal reaction conditions of T = 50 °C, 1.5 g/L of photocatalyst dosage, an oxidant to sulfur molar ratio of 6, and a solvent to fuel volume ratio of 1, the TxCZ sample exhibited superior performance by completely removing dibenzothiophene (DBT) from the model fuel. Kinetic studies indicate that the PODS reaction adheres to the pseudo-first-order kinetic model, with an observed activation energy of 69.25 kJ/mol−1.