Synergistic Effect and Mechanism of Bimetallic Cu-Zr Catalysts for Selective C-O Bond Hydrogenolysis

Lignin-derived aromatic alcohols are renewable biomass platform molecules for high-value biofuels, while selective benzylic C-O bond hydrogenolysis is hindered by competitive hydrogenolysis and hydrogenation. Cu-based non-noble catalysts are promising for selective C-O hydrogenolysis of lignin-derived aromatic alcohols due to their superior anti-aromatic hydrogenation ability, but suffer from low intrinsic activity and poor stability. Herein, a trace Zr-doped Cu10Zr0.11Ox bimetallic catalyst was prepared via a facile NaBH4 reduction method for selective C-O hydrogenolysis of vanillyl alcohol to 4-methylguaiacol. Benefiting from the strong metal-support interaction, the formed Cu-O-Zr synergistic interfaces regulate electronic redistribution, stabilize dominant Cu⁺ active sites, and enrich surface Lewis acidity. Appropriate Zr doping also refines Cu grains and optimizes catalyst structure, drastically reducing the apparent activation energy from 90.53 kJ/mol (pure CuOₓ) to 28.77 kJ/mol. The optimized Cu-Zr synergism modulates reaction kinetics to favor H2 dissociation and targeted C-O activation, enabling the catalyst to achieve >99.9% conversion and selectivity under mild conditions, with excellent substrate universality toward various lignin-derived aromatic alcohols and robust recyclability over five cycles. Mechanistic trapping and deuterium tracing experiments confirm that the reaction proceeds primarily via direct C-O bond cleavage, while radical, carbocation and dehydration-hydrogenation pathways are negligible or excluded. This work reveals the dual electronic and structural modulation effect of trace Zr doping, offering a feasible strategy for designing high-efficiency and stable Cu-based bimetallic catalysts for lignin valorization.