Effect of Hierarchically Macro-Mesoporous Structure of NiMoS/Al₂O₃ Catalysts on Hydrodesulfurization Activity

The thiophene-based compounds (such as 4,6-dimethyldibenzothiophene (4,6-DMDBT)) were removed with difficultly that since relatively larger molecules sizes with evident steric hindrance and worse accessibility of active sites during hydrodesulfurization (HDS) reactions. In this study, bimodal pore structure catalysts with higher specific surface areas, larger pore volume and mesoporous diameter were prepared. Moreover, less hydroxyl group in bimodal pore supports cause weaker metal-support interaction (MSI), which further contributes to the formation of Type-II active phase that possesses more active sites. The catalyst activity results of 4,6-DMDBT reveal that the bimodal pore catalyst with a narrow-distributed distribution of mesoporous size (NiMoS/S1) exhibited the highest apparent HDS activity and intrinsic activity for 4,6-dimethyldibenzothiophene. This work can deepen our understanding of the design of catalytic bimodal catalysts with high intrinsic activity and better accessibility of active sites.