Effect of catalyst preparation and support composition on hydrodesulfurization of dibenzothiophene and Maya crude oil

Hydrodesulfurization (HDS) of dibenzothiophene (DBT) was carried out in a batch reactor at 3.3 MPa and 340 °C. Sulfided catalysts showed a wide range of activity variation as a function of support composition, which established that sulfided active phases strongly depend on the nature and composition of support. The incorporation of MgO, SiO₂, TiO₂ and ZrO₂ with γ-Al₂O₃ alters the nature of active phase interactions on the support surface. Therefore, these oxides play a structural promoting role to the support contribution and its interaction towards the active metal geometry. Different preparation methods of catalysts were carried out by using different additives during the impregnation. It is demonstrated that co-impregnation method found better activity than sequential impregnation. The urea additive prepared catalyst provides promising activity compared with other chelating agents. An Al₂O₃-B₂O₃ mixed oxide supported catalyst was tested at high pressure with real feed (Maya heavy oil diluted with hydrodesulfurized diesel). The mixed oxide supported catalyst showed rapid deactivation with time-on-stream than the alumina supported catalyst that may be due to an enhancement in acidic sites. The activity results demonstrated that the number of catalytic sites is a combination of support composition, additive, impregnation pH, drying and calcinations of catalysts.