DFT Insights into Mg‐Modified Support Effects in Hydrodesulfurization: Mo─O Bond Weakening and Sulfur Vacancy Formation

Abstract In this research, the theoretical investigations were conducted to discuss the impact of Mg‐modification on the TiO 2 /Al 2 O 3 supported catalysts for regulating the MoO 3 precursor and the MoS 2 active phase in hydrodesulfurization (HDS). First, the DFT results verified that the Mg‐modification could effectively modulate the d‐band center of Mo in the MoO 3 precursor. Specifically, on Al 2 O 3 (100) and Mg‐Al 2 O 3 (100) surfaces, the d‐band centers of Mo atoms were calculated to be −1.25 eV and −0.04 eV, respectively. This significant shift in d‐band center directly affected the adsorption of pre‐sulfiding agents, thereby improving the sulfidation process. The COHP results also indicated that the Mo─O bond strength could be weakened after the addition of magnesium, clarifying that the incorporation of magnesium was favorable for the transformation process to the MoS 2 nanoclusters from MoO 3 . Additionally, the phase diagrams of sulfur vacancy formation revealed that Mg‐modification indeed had a significant impact on the sulfur vacancy formation processes, particularly on the Al 2 O 3 (100) surface where the effect was most pronounced. This study presented a synthesized strategy for MoS 2 ‐based catalysts with controllable sulfur vacancy concentration and helped establish rational design principles for future HDS catalysts.