Ru-Co bimetallic catalysts with synergistic crystalline phase regulation and hydrogen spillover for deep hydrodeoxygenation of lignin oil

The efficient hydrodeoxygenation (HDO) of lignin oil to produce high-value-added cycloalkanes is a key route for biomass resource utilization. However, developing catalysts with both high catalytic activity and product selectivity remains a crucial challenge in this field. Herein, a strategy integrating crystalline-phase regulation and hydrogen spillover was proposed. Ru was doped into the ZIF-67 precursor via a one-pot method. After controlled calcination and hydrogen reduction, a nitrogen-doped carbon-coated Ru-Co bimetallic catalyst (RuCo@NC) was successfully prepared. Characterization results showed that the introduction of Ru induced the phase transformation of Co from face-centered cubic (FCC) to hexagonal close-packed (HCP) and precisely regulated the electron density distribution of catalytic active sites through Ru to Co electron transfer. H 2 -TPR/TPD confirmed that Ru, as a hydrogen spillover site, significantly enhanced low-temperature reducibility and hydrogen adsorption capacity. DFT calculations indicated that Ru sites dominated the efficient dissociation and activation of H₂ molecules, while Co sites were responsible for the selective adsorption of substrate molecules. The synergistic effect between the two metals greatly improved the HDO activity of the catalyst. The optimized 0.009RuCo@NC-400 catalyst achieved 100% conversion of lignin oil at 240 °C and 2 MPa H₂, with a cycloalkane selectivity of 73.7%. Moreover, the conversions of ten lignin derivatives were all above 97%. This study reveals a synergistic catalytic mechanism of the 0.009RuCo@NC-400 catalyst, integrating crystalline phase structure, electronic effects, and hydrogen spillover, providing theoretical guidance for the design of efficient HDO catalysts.