Deep hydrodesulfurization over Co/Mo catalysts supported on oxides containing vanadium

TiO2–ZrO2 and γ-Al2O3 supports were modified by impregnation with a vanadium salt. The hydrodesulfurization (HDS) of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (46DMDBT) showed that the selectivity of the hydrogenation (HYD) pathway was greatly increased by this modification. The ratio of HYD to direct desulfurization (DDS) pathway in the HDS of DBT over CoMo/(V2O5/TiO2–ZrO2) was 3.1 and over CoMo/(V2O5/γ-Al2O3) it was 0.9. The reactivity of DBT over CoMo/γ-Al2O3 was higher than that over CoMo/(V2O5/TiO2–ZrO2), while the opposite was true for the reactivity of 46DMDBT, which was due to the higher hydrogenation activity, and the more acidic sites of the impregnated V2O5 and the mixed metal-oxides supports. Temperature-programmed reduction indicated that CoO–MoO3 on the TiO2–ZrO2 and V2O5 modified supports was more reducible and possibly has a different morphology than on γ-Al2O3. Furthermore, the results of X-ray photoelectron spectroscopy indicated that the impregnated V2O5 affected the interaction between MoS2 and the supports. Thus, the synergetic effect of binary V–Mo sulfides could induce active sites to facilitate the HYD pathway.