Bimodal mesoporous AlMCM-41 supported NiMo catalysts for efficient hydrodesulfurization of 4,6-dimethyldibenzothiophene

In this research, a bimodal mesoporous AlMCM-41 (B-AM41) material was prepared and applied to support NiMo catalysts for the hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene. Additionally, catalysts supported on smaller and larger single-pore AlMCM-41 (S-AM41 and L-AM41) were also prepared as reference catalysts. Detailed characterizations show that the proportion, stacking degree, and length of the MoS₂ active phase on the different catalysts are distinct. As a result, HDS evaluation indicates that the NiMo/B-AM41 catalyst exhibited better catalytic activity with a reaction rate constant of 10.4 × 10⁻⁸ mol g⁻¹ s⁻¹ and a turnover frequency of 7.0 × 10⁻⁴ s⁻¹, significantly surpassing the S-AM41 and L-AM41 supported catalysts. The superior activity of the NiMo/B-AM41 catalyst can be attributed to a high sulfidation degree that provides sufficient highly dispersed type Ⅱ MoS₂ phases with minimal stacking and moderate slab length. Moreover, the bimodal mesoporous structure promotes the diffusion of 4,6-DMDBT and benefits its contact with active sites.