Effect of synthesis temperature on structure-activity-relationship over NiMo/γ-Al2O3 catalysts for the hydrodesulfurization of DBT and 4,6-DMDBT

Abstract

A series of γ-Al2O3 materials with different textural properties and acidities were synthesized from the boehmite sol by tuning the aging temperatures. NiMo supported catalysts were prepared by using γ-Al2O3 as the supports, then the catalytic HDS performance were evaluated by using DBT and 4,6-DMDBT to be the probe molecules. The physico-chemical properties of γ-Al2O3 supports and the corresponding NiMo catalysts were characterized by XRD, N2-physisorption, Py-IR, UV–Vis DRS, laser Raman spectra, H2-TPR, XPS, HRTEM methods. The characterization results showed that NiMo/γ-363 catalyst possessed a large pore size (12.0nm), open pore volume (0.86cm3g−1), moderate acidity and appropriate MSI. The NiMo/γ-363 catalyst presented the highest DBT and 4,6-DMDBT conversions at all the WHSVs. The NiMo/γ-363 catalyst showed highest kHDS and TOF values of the 4,6-DMDBT HDS, which could be ascribed to the synergistic effect of excellent textural properties, appropriate acidity and suitable MSI of the NiMo/γ-363 catalyst, moderate dispersion degree, high sulfidation degree and desirable stacking morphology of the MoS2 crystallites. The highest HYD/DDS ratio (1.51) of the 4,6-DMDBT HDS over the NiMo/γ-363 catalyst indicated that the HYD pathway was the main reaction route. Furthermore, a possible reaction network for 4,6-DMDBT HDS over the series of NiMo/γ-Al2O3 catalysts was proposed.