Effects of Titania Coatings on Hydrodesulfurization Catalysts: Insights from First-principles Calculations

First-principles calculations were carried out with Al₂O₃ as the catalyst support and MoS₂ as the supported metal species, focusing on the TiO₂ coating and support-metal interaction to establish guidelines for the development of high activity hydrodesulfurization catalysts. MoS₂ clusters were modeled on the surfaces of Al₂O₃ and TiO₂ and the adsorption energy was calculated. TiO₂ showed stronger interaction with MoS₂ than Al₂O₃. MoS₂ clusters were also modeled on Al₂O₃ supports coated with thin films of TiO₂, and the adsorption energy was calculated. Adsorption energy depended on the number of stacked film layers, suggesting that thin film thickness can be optimized. An amorphous Al₂O₃ support model was created to approach the real surface state and adsorption calculations were performed. Adsorption energy was higher than with a crystalline support, and the presence of sites where more stable adsorption would occur was confirmed.