Hydrodesulfurization catalyzed by zeolite-supported

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We intended to promote the hydrodesulfurization reactivity of dimethyldibenzothiophenes, 4,6-dimethyldibenzothiophene, in particular, by utilizing the acidity of zeolites, which promotes demethylation or methyl-transfer reaction. We have successfully incorporated a molybdenum sulfide cluster, [Mo_3S_4(H_2O)_9]^<4+> with incomplete cubane-type structure and molybdenum-nickel cluster with complete cubane-type structure into zeolites with 12-membered ring by aqueous ion exchange. Control catalysts Mo/Al_2O_3 and MoNi/Al_2O_3 were also prepared by impregnating Al_2O_3 with the solution of ammonium heptamolybdate and nickel nitrate followed by presulfiding. In the preparation of Mo/KL and Mo-MOR,the ion exchange was found to be sluggish and the degree of exchange was as low as 20%. However, Mo/KL and showed higher HDS activity than Mo/NaY in spite of its lower molybdenum loading. Involvement of Ni resulted in great enhancement of HDS activity ; however, MoNi/KL proved to be less active for HDS of benzothiophene than NiS-MoS_2/Al_2O_3 catalyst. In contrast, MoNi/KL showed higher activity for HDS of 4,6-dimethylbenzothiophene than NiS-MoS_2/Al_2O_3 catalyst. From the analysis of the product distribution, it is concluded that this high activity of MoNi/KL is due to the conversion of the reactant to more reactive ones through demethylation or methyl-transfer reaction promoted by acidity of the catalyst.