Tri-Site Synergy in CuCoCe Catalysts: Unlocking Selective Hydrodeoxygenation Pathways of Dicarboxylic Acid Dimethyl Esters via Site-Specific Activation

Hydrodeoxygenation (HDO) of biomass-derived dicarboxylic acid dimethyl esters (DAMEs) into alkanes, diols, or high-value-added chemicals facilitates the replacement of fossil resources with renewable organic alternatives. While substantial progress has been achieved in the HDO of dimethyl oxalate (DMO), investigations into the HDO of other C₂₊ DAMEs and comprehensive mechanistic studies on multisite synergies and chain-length effects remain scarce. Consequently, we designed ternary CuCoCe catalysts via coprecipitation with definite trisite synergy for the selective HDO of DAMEs with varying chain length. The Cu₁Co₂Ce₁-300 catalyst demonstrated optimal HDO activity, with 100% DAME conversion and a 100% yield of ethylene glycol (C₂) or C₃–C₉ alkanes, under 5 MPa H₂ at 240 °C for 4 h. In conjunction with the experimental results, systematic characterizations revealed the definite trisite synergistic effect: Cu species enhance hydrogenation, Co species promote deoxygenation and ring-opening, and Ce species boost the adsorption/activation of oxygen-containing functional groups. Moreover, the chain-length-dependent HDO mechanisms of DAMEs over the ternary CuCoCe catalysts were comprehensively analyzed. Finally, the recyclability of the catalyst was investigated, which presents no significant changes in catalytic performance and catalyst structure after five consecutive runs.