Supported phosphotungstic-based ionic liquid as an heterogeneous catalyst used in the extractive coupled catalytic oxidative desulfurization in diesel

摘要

In order to effectively catalyze the oxidation of dibenzothiophene (DBT) in diesel, a phosphotungstic-based ionic liquid (IL) supported catalyst [C(16)mim](3)PW12O40/TiO2 was prepared through a one-step method. Commercially available TiO2 (C-TiO2), a type of transition metal oxide, was selected as a carrier for comparison. The structure and composition of the catalysts were studied through TG, FT-IR, UV-DRS, wide-angle XRD, N-2 adsorption-desorption, SEM and XPS analysis. It was found that the Keggin structure of [C(16)mim](3)PW12O40 was still preserved in the supported catalysts. In addition, the catalysts were applied in extractive coupled catalytic oxidative desulfurization (ECODS) system with H2O2 participating, and dibenzothiophene (DBT) could be totally removed after 1 h under optimum conditions. In addition, factors that affected the desulfurization efficiencies were also been studied in detail. The oxidation product after the reaction was detected by means of GC-MS analysis, DBTO2 (m/z = 216.0) was proved to be the only product of DBT and the possible mechanism was proposed. Moreover, the reusability of the supported ionic liquid catalyst was also investigated, and the oxidation of DBT could still reach 97.8% after eight cycles.