Tetradecylamine-induced assembly of Mo and Al precursors to prepare efficient NiMoS/Al2O3 catalysts for ultradeep hydrodesulfurization

Novel alumina-supported Ni-Mo hydrodesulfurization (HDS) catalysts were prepared via assembly of Mo and Al precursors induced by tetradecylamine (TDA). Compared with conventional impregnation, this assembly method improves Mo dispersion, weakens metal-support interactions, enhances Ni modification at MoS2 edge sites, and produces more NiMoS phases on Al2O3. The optimal NiMoS microstructure was obtained by modulating the TDA/Mo ratio in the assembly. A microstructure-activity correlation indicated that the S vacancies at the NiMoS corner sites favored σ-adsorption and direct desulfurization of 4,6-dimethylbenzothiophene (4,6-DMDBT), and those at the NiMoS edge sites promoted C-S breaking in hydrogenated derivatives of 4,6-DMDBT. Among these catalysts, NiTMo-2.0/Al2O3, which had the most corner and edge S vacancies, exhibited the highest reaction rate constant of 5.89 × 10−7 mol·g−1·s−1 and the highest desulfurization ratio of 99.5% in HDS of 4,6-DMDBT.