This study systematically investigates the synthesis of mesoporous δ-Al 2 O 3 supports via a controlled sol–gel method and their application in NiMo-catalyzed hydrodesulfurization (HDS) of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). Advanced characterization reveals that the textural and acidic properties of the δ-Al 2 O 3 supports can be precisely tailored, which subsequently modulates the metal-support interaction, governs the sulfidation behavior, determines the active phase morphology, and ultimately regulates the HDS performance. Among the series, the catalyst supported on δ-Al 2 O 3 aged at 50 °C (denoted as NiMo/δ-50) demonstrated an optimal combination of high surface area, large pore volume, and moderate acidity. This optimal support structure, accompanied by an appropriate metal-support interaction, facilitated the formation of a highly active phase characterized by a superior Mo sulfidation degree (69%), a high proportion of NiMoS sites (90.2%), and MoS 2 slabs with optimal stacking. Consequently, this catalyst achieved outstanding HDS activity, with near-complete DBT conversion (99.9%) and 94.3% conversion of the sterically hindered 4,6-DMDBT. This work underscores the pivotal role of support engineering in regulating metal-support interaction and provides a rational design strategy for advanced HDS catalysts.
