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The aggregation of nanoparticle catalysts is one of the main problems in catalytic reactions. In this study, a series of TiO 2 nanoparticle catalysts with various dispersions were prepared and applied in the catalytic oxidation of dibenzothiophene (DBT) systems. Compositions and structures of the as-prepared samples were analyzed by means of wide-angle X-ray diffraction, Raman and X-ray photoelectron spectroscopies. The dispersions of TiO 2 nanoparticles were controlled by calcining at various temperatures and verified using transmission electron microscopy. It was found that the activities of TiO 2 nanoparticles in the catalytic oxidation of DBT were positively correlated with the dispersions. TiO 2 nanoparticles calcined at 500°C (500-TiO 2 ) showed the best catalytic activity and the oxidation of DBT reached 99.8% under mild conditions. Based on the results of GC-MS analysis, radical trapping experiments and electron spin resonance spectra, • O 2 − radicals were proved to be the main active species in the oxidation process, and a mechanism is proposed. Meanwhile, the recycling performance of 500-TiO 2 was investigated, and no obvious decrease was observed after six recycles.

Supported ionic liquid (IL) catalysts [C n mim] 3 PMo 12 O 40 /Am TiO 2 (amorphous TiO 2) were synthesized through a one-step method for extraction coupled catalytic oxidative desulfurization (ECODS) system. Characterizations such as FTIR, DRS, wide-angle XRD, N 2 adsorption-desorption and XPS were applied to analyze the morphology and Keggin structure of the catalysts. In ECODS with hydrogen peroxide as the oxidant, it was found that ILs with longer alkyl chains in the cationic moiety had a better effect on the removal of dibenzothiophene. The desulfurization could reach 100% under optimal conditions, and GC-MS analysis was employed to detect the oxidized product after the reaction. Factors affecting the desulfurization efficiencies were discussed, and a possible mechanism was proposed. In addition, cyclic experiments were also conducted to investigate the recyclability of the supported catalyst. The catalytic activity of [C 16 mim] 3 PMo 12 O 40 /Am TiO 2 only dropped from 100% to 92.9% after ten cycles, demonstrating the good recycling performance of the catalyst and its potential industrial application.