Sulfured NiMo catalysts on TiO2-Nb2O5 nanocomposites for efficient hydrodesulfurization performance

The implementation of increasingly stringent environmental regulations has increased the demand for more active catalysts in hydrotreating. This study proposes the synthesis, characterization, and evaluation of bimetallic NiMo catalysts supported on TiO2-Nb2O5 nanocomposites for dibenzothiophene hydrodesulfurization. Samples containing 3, 5, and 10 wt.% Nb were synthesized to examine the influence of Nb content on their catalytic activity and selectivity. Supports and oxidized catalysts were characterized using various techniques, including SEM-EDX, N2 physisorption, powder XRD, UV-vis DRS, Raman spectroscopy, and H2-TPR, while sulfured catalysts were further characterized by XPS and HRTEM. NiMo/TiNb3 and NiMo/TiNb5 catalysts displayed propene and diisopropyl ether as the main products in the 2-propanol dehydration reaction. Furthermore, a correlation was observed between hydrogenating capabilities in the HDS and dehydration tests with the Nb loading, suggesting that an optimal combination of Lewis/Brønsted acid sites enhances the BP/CHB ratio. All Nb-containing samples exhibited superior activity compared to their Nb-free counterpart, as indicated by the higher values of the pseudo-first-order rate constants (kHDS), which were higher for the NiMo/TiNb3 catalyst. These results were also associated with the respective textural characteristics, metal dispersion, and species distribution.