A facile sol–gel method based on urea–SnCl2 deep eutectic solvents for the synthesis of SnO2/SiO2 with high oxidation desulfurization activity
Silica gel containing SnCl2-based deep eutectic solvents (DESs) were synthesized by a sol–gel method using SnCl2-based DESs as the loading component. The n%-SnO2/SiO2 (n = 2, 4, 6) supported catalyst was obtained by calcination of silica gel containing SnCl2-based DESs at high temperature. n%-SnO2/SiO2 was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 adsorption–desorption and X-ray photoelectron spectroscopy (XPS). A catalytic oxidation desulfurization system with 4%-SnO2/SiO2 as the catalyst and H2O2 as the oxidant was applied to remove organic sulfide in model oil. Compared with the traditional impregnation method, the catalyst synthesized using the sol–gel method showed higher oxidative desulfurization activity. The effects of various factors including loading dose of SnO2, temperature, O/S molar ratio, catalyst dosage, and different sulfides on the desulfurization rate were investigated. The experimental results indicate that the desulfurization rate of dibenzothiophene (DBT), 4,6-dimethyldibenzothiophene (4,6-DMDBT) and benzothiophene (BT) can reach 99.5%, 81.6% and 22.4%, respectively, under the optimal reaction conditions. The desulfurization activity of 4%-SnO2/SiO2 is above 90% after recycling 5 times.