HDS performance of sulfided CoMoW/Nb-SBA-15 catalysts: effect of Nb content

In this work, the catalytic performance of sulfided CoMoW/Nbx-SBA-15 systems was investigated in the hydrodesulfurization (HDS) of dibenzothiophene (DBT). Nbx-SBA-15 substrates with nominal Si/Nb molar ratios of 80, 100, and 120 were prepared via a direct sol–gel method and characterized by XRD, UV–vis DRS, N2 adsorption–desorption isotherms, XRF, FESEM, EDS, and pyridine-adsorbed FTIR, along with catalytic performance tests. The Nbx-SBA-15 materials exhibited both Brønsted and Lewis acid sites, whose concentrations increased with increasing Nb content. Incorporation of niobium, both within the SBA-15 framework and as well dispersed extra-framework species, led to enhanced catalytic activity of the sulfided CoMoW catalysts compared to the Nb-free sample. This improvement is mainly associated with the Nb-induced increase in surface acidity and modified metal–support interaction effects, which contribute to improved dispersion of the active sulfided phases. Catalytic activity showed a nearly linear dependence on Nb content, reaching a maximum at a Si/Nb molar ratio of 80. These results demonstrate that controlled Nb incorporation efficiently tunes the acidic and structural properties of SBA-15 while preserving its ordered mesoporous morphology, resulting in enhanced HDS performance.