Mild selective hydrogenolysis of lignin-derived aryl ethers over Ni/CeO2 catalyst: Targeted cleavage of C-O bonds

• 500 °C calcination maximizes oxygen vacancies (O v ) with abundant phase interfaces. • Synergistic Ni-O v dual sites promote substrate adsorption and C-O bond cleavage. • Ni/CeO 2 -500 achieves 100% BPE conversion exclusively to toluene/phenol at 100 °C. • DFT calculations show C-O scission energetically favored over arene hydrogenation. Developing simple and efficient catalytic systems for cleaving bridged linkages in lignin has emerged as a promising valorization strategy. In this work, a series of Ni/CeO 2 catalysts calcined at 400-800 °C were prepared and evaluated for the selective hydrogenolysis of lignin-derived aryl ethers. Among them, Ni/CeO 2 -500 demonstrated optimal activity, achieving complete conversion of benzyl phenyl ether (BPE) at 100 °C with 100% selectivity to toluene and phenol (no detectable arene hydrogenation byproducts). For the more robust β-O-4 and 4-O-5 model compounds, 71%-100% conversion with 81.22%-100% selectivity to aromatic monomers were attained at 180°C. Catalyst characterization revealed that calcination at 500 °C optimized oxygen vacancy (O v ) concentration as evidenced by XPS analysis of O III /O I +O II ratio and Ce³⁺/Ce⁴⁺ ratio. Furthermore, density functional theory (DFT) calculations elucidated a dual-site mechanism: Ni sites facilitate H₂ dissociation and interaction with aromatic rings, and adjacent O v sites activate C-O bonds via coordination to oxygen-containing functional groups. The synergistic Ni-O v cooperation enhances substrate adsorption and lowers the C-O bond dissociation energy by 1.04-1.32 eV, thereby promoting selective hydrogenolysis over arene hydrogenation at lower temperatures. The Ni/CeO₂-500 system demonstrates significant potential for efficient lignin depolymerization under mild conditions, offering new insights for designing non-noble metal catalysts in biomass valorization.