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A deep hydrodesulfurization (HDS) catalyst, which was considerably active to desulfurize dibenzothiophene (DBT) and 4, 6-dimethyldibenzothiophene (4,6-DMDBT), was prepared by depositing Ni-Mo species over SBA-15. The extremely high surface area of SBA-15 favors the dispersion of the active species, which result in very high HDS activity. The optimal Ni/Mo atomic ratio for this series of catalysts is 0.25. Ni-Mo(0.25)/SBA-15 exhibited excellent performance in HDS of DBT and 4,6-DMDBT.

NiMoS/Al 2 O 3 catalysts, prepared by selectively depositing Ni on MoS 2 /Al 2 O 3 by a chemical vapor deposition (CVD) method, showed a higher activity in the hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene (4,6-DMDBT) and dibenzothiophene (DBT) than those containing Ni added by impregnation. The activities were different between two types of catalysts because the Ni species added by CVD interacted more intimately with the MoS 2 surface than those added by impregnation, which was confirmed by comparing the X-ray photoelectron spectra (XPS) and the results of elemental analyses of the catalysts. Between two major routes of the HDS, the direct desulfurization (DDS) route was promoted to greater extents than the hydrogenation (HYD) route when the Ni species were added by CVD instead of impregnation.

The kinetics of dibenzothiophene (DBT) hydrodesulfurization (HDS) over Ni-Mo/MCM-41 catalysts were studied on a high-pressure, fixed-bed flow microreactor at temperatures of 260 °C to 320 °C and total pressure of 5.0MPa. DBT solutions of different concentrations were used in order to investigate the effect of DBT concentration on HDS reaction rate. The hydrodesulfurization reactions were found to proceed via a network involving hydrogenolysis pathway and hydrogenation pathway. And cyclohexyl benzene and biphenyl generated during DBT are subject to hydrocracking to yield benzene and hexane. Accordingly, the rates of HDS, hydrogenolysis pathway, hydrogenation pathway and hydrocracking pathway were determined by means of the pseudo-first-order model. And their activation energies were estimated.

Deep hydrodesulfurization (HDS) catalysts were prepared by depositing Co−Mo or Ni−Mo species over siliceous MCM-41. The extremely high surface area of MCM-41 favors the dispersion of the active species, resulting in a very high reactivity in desulfurizing dibenzothiophenes. A maximum HDS activity was observed at Co/Mo or Ni/Mo molar ratio of 0.75 for the supported catalysts, higher than that of the conventional γ-Al 2 O 3 supported catalysts. A 35 S isotope tracer technique was used to investigate the HDS reaction mechanism. It was revealed that sulfur atoms retained on the surface could be removed only by the introduction of a sulfur-containing compound, indicating that sulfur atom exchange between sulfur-containing compounds and the active sites is involved in the HDS reaction. Accordingly, a reaction mechanism for HDS is proposed.