Superior Hydrodesulfurization Catalyst Prepared via Hydrothermal Deposition of Lacunary NiPW Polyoxometalate on γ-Al ₂ O ₃

A highly efficient hydrodesulfurization (HDS) catalyst was fabricated by hydrothermal deposition of a lacunary Ni 6 PW 9 polyoxometalate (POM) precursor onto γ-Al 2 O 3 . The optimized catalyst possesses a nominal composition of 20 wt % WO 3, 4.3 wt % NiO, and 0.68 wt % P 2 O 5, identical to that of the reference catalyst prepared via conventional impregnation. Quantitative characterizations reveal that the optimized catalyst exhibits homogeneous metal dispersion, a higher sulfidation degree of W species (58% vs 43%), an increased proportion of the NiWS active phase (46% vs 37%), shorter WS 2 crystallites (2.6 nm vs 3.2 nm), and a higher average stacking number (3.1 vs 2.8) in comparison with those of the reference counterpart. When evaluated using dibenzothiophene (DBT) as the model compound, the optimized catalyst achieves a DBT conversion of 94% and a turnover frequency of 1.02 × 10 –3 s –1, which are 1.4 and 1.5 times, respectively, those of the reference catalyst. Meanwhile, the catalyst exhibits enhanced direct desulfurization selectivity with a BP/CHB ratio of 4.6, remarkably higher than that of the reference catalyst. The superior HDS performance is attributed to atomic-level mixing of Ni, W, and P elements in the POM precursor, weakened metal–support interaction, and a favorable microstructure of the active phase. This work provides a feasible and controllable strategy for designing high-performance HDS catalysts through hydrothermal deposition of well-defined POM precursors.