Hydrogen spillover network-driven hydrodeoxygenation of lignin Oil:Ni-Ru bimetallic synergy and oxygen vacancy engineering for high-selectivity cycloalcohol production

This study addresses the key demands for the hydrodeoxygenation (HDO) of real lignin oil to produce high-value chemicals. A Ni-Ru bimetallic catalyst (Ni-Ru@TiO 2 -HT) based on an alkali-modified TiO 2 support was designed and successfully prepared. Commercial TiO 2 was transformed into layered sodium titanate nanorod supports (denoted as TiO 2 -HT) through a high-concentration NaOH hydrothermal method, and Ni and Ru active components were loaded by a hydrothermal reduction method. Systematic characterizations indicated that this strategy successfully constructed a synergistic catalytic system with highly dispersed metal sites and abundant oxygen vacancies. Mechanism analysis revealed that the electron-rich Ru centers preferentially split hydrogen to generate active hydrogen atoms, which were transferred to Ni sites and oxygen vacancies via hydrogen spillover, achieving efficient activation and cleavage of C-O and C=O bonds in lignin oil molecules. The strong metal-support interaction (SMSI) formed by the Ni-Ru alloy and oxygen vacancies further enhanced the interfacial synergy of the catalyst, significantly improving its catalytic activity, durability, and product selectivity. In catalytic performance tests, the Ni-Ru@TiO 2 -HT catalyst achieved a conversion rate of over 99 % for the GC-detectable monomers in real lignin pyrolysis oil, with a selectivity of 45 % for the target product cyclohexanol and a total selectivity of over 96 % for cycloalcohols. This work provides a reasonable design strategy for multi-metallic catalysts, balancing their activity and selectivity, which is conducive to converting lignin oil into biofuels and high-value-added alcohol chemicals.