Local electron transfer in RuNi alloy catalysts for selective hydrogenolysis of lignin-derived C−O bonds

Selective hydrogenolysis of C−O bonds in lignin offers a promising pathway for biomass valorization but remains challenging due to competing aromatic ring hydrogenation. Herein, we report an efficient RuNi alloy catalyst synthesized via a solvent-free microwave-assisted pyrolysis strategy that enables highly selective hydrogenolysis of C−O bonds in lignin-derived benzyl phenyl ether (BPE). A volcano-type dependence of catalytic performance on the Ru/Ni ratio was observed, with the optimized Ru 2 Ni 2 /MgAl 2 O x catalyst achieving 99.5% conversion and 84.2% hydrogenolysis selectivity for BPE under mild conditions (160 °C, 4 h), corresponding to a 1.7-fold enhancement in hydrogenolysis rate compared to monometallic Ru. The catalyst further demonstrated broad applicability toward diverse lignin-relevant ether linkages, including 4-O-5 (85.2% selectivity) and β-O-4 bonds (72.8% selectivity). Comprehensive characterization combined with DFT calculations reveal that electron transfer from Ni to Ru (1.27 e⁻) drives the formation of the RuNi alloy with a Ni δ+ -Ru δ- electronic structure, which regulates adsorption and bond activation simultaneously. The tailored electronic structure suppresses benzene ring adsorption, reducing the BPE adsorption energy to −3.30 eV, while enhancing local electron transfer (0.154 e⁻) within the Ni δ+ -Ru δ- -O configuration to weaken the C−O bond and accelerate hydrogenolysis. This work provides a promising strategy for the rational design of alloy catalysts via electronic structure modulation toward the selective hydrogenolysis of lignin-derived ethers. • RuNi alloy catalysts were fabricated via a microwave-assisted pyrolysis method. • The Ru 2 Ni 2 alloy catalyst achieves a high α-O-4 bond hydrogenolysis rate of 418 mmol mmol Ru -1 h -1 . • Significant local electron transfer (0.154 e - ) in the Ru 2 Ni 2 alloy effectively weakens C−O bonds. • The Ru 2 Ni 2 alloy catalyst exhibits versatility for the hydrogenolysis of diverse lignin-derived C−O bonds.