Metal oxide nanoparticles (NPs) have been regarded as highly active species for many catalytic processes but are being seriously hindered by their agglomeration property. In this work, graphite carbon (GC) is employed as a carrier for the dispersion and stabilization of TiO2 NPs to overcome the disadvantage. A series of supported catalysts TiO2/GC with different loading amounts of TiO2 are prepared and characterized in detail. It is discovered that TiO2 NPs are well dispersed on GC when the loading amount is 10%, which is confirmed by elemental mapping and transmission electron microscopy images. As expected, the supported 10%-TiO2/GC catalyst reveals outstanding catalytic activity in the oxidative removal of dibenzothiophene (DBT). A 100% desulfurization efficiency is obtained under mild reaction parameters. Meanwhile, the kinetic parameter investigation shows that the oxidation of DBT followed the pseudo-first-order kinetic model. In addition, the mechanism of the oxidative desulfurization system is studied carefully by free-radical scavenging experiments, electron spin resonance, Raman spectroscopy, and gas chromatography–mass spectrometry analysis. Moreover, the supported catalyst possesses excellent stability and recycling performance, and the removal of DBT remains to be >99% after five times of recycling.

Functionalized ionic liquids (ILs) have been considered as efficient catalysts for oxidative desulfurization (ODS), but the further industrial applications are hampered by the poor separability with oil phase after reaction and large dosage. In this work, few-layered graphitic carbon nitride (g-C 3 N 4 ) with high specific surface area was prepared via thermal oxidation and employed as a carrier to construct supported ionic liquid catalyst for ODS. A functional quaternary phosphonium ionic liquid [(C 6 H 13 ) 3 PC 14 H 29 ] 3 PMo 12 O 40 (abbreviated as C 14 PPMo) was synthesized and immobilized on g-C 3 N 4 . Then, the as-prepared samples were characterized by FT-IR, DRS, XRD, N 2 adsorption−desorption isotherm, XPS, SEM, and TEM, systematically. It was found that few layer g-C 3 N 4 had a large specific surface area (194.89 m 2 g −1 ), which was conducive to the high dispersion of C 14 PPMo IL. The obtained support catalyst C 14 PPMo/g-C 3 N 4 exhibited outstanding catalytic ability on the oxidation of dibenzothiophene (DBT), and the desulfurization efficiency could reach 100% with a small dosage of IL under optimal conditions. The oxidative products of DBT and 4,6-dimethyldibenzothiophene (4,6-DMDBT) were the homologous sulfones and proved by GC-MS, and the proposed reaction processes were studied, respectively. Since the supported IL was a heterogeneous catalyst and no additional solvent was added, C 14 PPMo IL could be separated and repossessed readily after the reaction. Moreover, the recycle ability of C 14 PPMo/g-C 3 N 4 on the oxidation of both DBT and 4,6-DMDBT were investigated simultaneously, and both of the desulfurization activities could still remain above 90% after 6 times cycling.