Ni–Mo Interfacial Electronic Transfer and Acid-Site Coupling Drive Carbon-Backbone-Retentive Hydrodeoxygenation of Fatty Acid Esters under Mild Conditions

Biodiesel, a renewable and carbon-neutral fuel, offers a sustainable alternative to petroleum diesel. However, its widespread application is hindered by the need for energy-intensive deoxygenation processes that often degrade the carbon backbone of fatty acid esters. This study presents a non-noble NiMo/HBeta bifunctional catalyst for the complete conversion of methyl stearate under mild conditions (190 °C), achieving 92.53% selectivity toward C18 alkanes and a high HDO/DCO (hydrodeoxygenation/(decarboxylation + decarbonylation)) ratio of 12.38, outperforming previously reported catalytic systems. Mechanistic insight reveals that atomically dispersed Ni δ+ –MoO x sites enable directed electron transfer from Ni to Mo. This creates a synergistic interface where Ni activates H 2 while Mo polarizes the C=O bond, lowering the barrier of the HDO pathway to 1.76 eV and kinetically favoring carbon-retentive deoxygenation. Concurrently, Mo reshapes the acid properties by suppressing strong Brønsted sites, establishing a Lewis-acid-dominated microenvironment that selectively cleaves C–O bonds while inhibiting C–C scission. This work elucidates how interfacial electronic synergy and tailored acidity cooperatively steer reaction pathways, offering a design principle for efficient biomass upgrading under mild conditions.