| The traditional hydrodesulfurization (HDS) technology is facing challenges due to more and more stringent sulfur content standards. Therefore, many works has been done to develop the other alternative efficient desulfurization methods. Oxidative desulfurization (ODS), which can be carried out under mild conditions, is the important one among theses new technologies. The ODS process can be run independently or following the HDS process in a refinery plant. The focus of this thesis is to study the oxidative desulfurization performances the molybdenum-based heterogenous catalysts using heterocyclic sulfur-containg compounds as the model molecules.The MoO3-CeO2-SiO2 mix oxide catalyst was prepared by a Sol-gel procedure. The optimum Mo/Si and Ce/Si molar ratio was 0.1 and 0.02, respectively. The catalyst was characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results indicated that the introduction of CeO2 facilitated the dispersion of MoO3 over SiO2, and the Mo6+ was the predominant species in MoO3/SiO2, whereas Mo5+ species appeared after the introduction of CeO2. The catalytic performance of MoO3-CeO2-SiO2 in the ODS of 0.2 wt.% dibenzothiophene (DBT) in toluene with cumene hydroperoxide as the oxidant was investigated at 40℃and an oxygen/sulfur (O/S) molar ratio was 3.0. The DBT conversion reached 94.2% within 8 h using a fix-bed reactor.The [Bmim]3PMo12O40/SiO2 solid catalyst was prepared by H3PMo12O40, [Bmim]Br ionic liquid and SiO2. The catalytic performance of [Bmim]3PMo12O40/Si02 was tested in the ODS of 0.2 wt.% DBT in toluene in a batch reactor using H2O2 as the oxidant. The [Bmim]3PMo12O40/SiO2 is amphiphilicity, which enhances adsorption of both H2O2 and sulfur-containing compounds. The maximum activity was observed at a loading of 20 wt.% [Bmim]3PMo12O40 on SiO2, and 100% DBT conversion was achieved at 60℃and O/S molar ratio was 3.0 within 100 min. The solid catalyst could be easily separated by centrifugation, and reused without deactivation after seven runs with drying. The oxidation of benzothiophene (BT), DBT, and 4,6-dimethyl dibenzothiophene (4,6-DMDBT) in [Bmim]3PMo12O40/SiO2-H2O2 system were also investigated, and the reactivity of these sulfur-containg compounds decreased in the order:DBT>4,6-DMDBT>BT due to the electronic density of sulfur and the stereo-hindrance effect. The oxidative desulfurization of diesel was carried out at 80℃and O/S molar ratio 5.0 within 180 min followed by dimethylformamide extraction, and the sulfur content of diesel decreased from 530 to 11 ppm. The oxidation of indole, quinoline, and carbazole in [Bmim]3PMo12O40/SiO2-H2O2 system was studied. The reactivity of these molecules decreased in the order:indole> quinoline> carbazole. The oxidation of indole, quinoline, and carbazole in [Bmim]3PMo12O40/SiO2-H2O2 system was studied. The reactivity of these molecules decreased in the order:indole> quinoline>carbazole. The effect of nitrogen-containing compounds on oxidation of DBT was also investigated. The results indicated that the quinoline and carbazole had slightly positive effects on DBT oxidation, whereas indole had a negative effect.SiO2 was modified with 1-triethoxysilylpropyl-3-methylimidazolium chlorid by grafting method. The H3PMo12O40 was immobilized onto the modified SiO2 (ILSiO2) to prepare the PMo/ILSiO2 catalyst. The characterization of PMo/ILSiO2 indicated that the hybrid molecular material possessed the Keggin structure of [PMo12O40]3- and the Bmim cation. The ODS performance of DBT was tested in batch reactor using the H2O2 as the oxidant. The maximum activity was observed at a H3PMo12O40 loading of 30 wt.%, and 100% DBT conversion was achieved at 50℃and an O/S molar ratio of 3.0 in 30 min.
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