Flower-like hierarchical TS-1/Al2O3 composite supported NiMo catalysts for efficient hydrodesulfurization of dibenzothiophenes

Flower-like Al₂O₃ materials were successfully incorporated by TS-1 nanocrystals to synthesize Flower-like TS-1-Al₂O₃ (FTA) micro-mesoporous composite by a facile nano self-assembly method. FTA supported NiMo bimetallic catalysts (NiMo/FTA) were further constructed and applied to the hydrodesulfurization (HDS) reactions for dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). FTA composites were constructed from flower-like pore structures stacked with nanosheets, which are conducive to the even load and dispersion of active species and the diffusion of macromolecular sulfur-containing compounds with relatively low resistance. The fabrication of TS-1 nanocrystals effectively enhanced the acidic sites, regulated the metal-support interaction, which could increase the stacking layer of MoS₂ slabs, and producing more NiMoS-II type active phase. NiMo/FTA-10 presented the excellent HDS conversion of DBT (99.3 %) and 4,6-DMDBT (93.2 %) at 10 h⁻¹, the highest reaction rate constant (2.6 × 10^-7 mol g⁻¹ s⁻¹) and turnover frequency values (6.7 × 10^-4 s⁻¹) for 4,6-DMDBT HDS reaction. Compared to the direct desulfurization route (DDS), hydrogenation route (HYD) and isomerization route (ISO) can effectively eliminate the steric hindrance of 4,6-DMDBT, which is more conducive to the HDS reaction.