Selective hydrodeoxygenation of lignin-derived 2,6-dimethoxy-1,4-benzoquinone to 1,4-cyclohexanediol via Ru/CeO ₂ catalyst in water

The selective valorization of lignin-derived quinones into high-value aliphatic alcohols is a sustainable yet challenging route for biomass upcycling, particularly in environmentally benign media. Herein, we report a robust catalytic strategy for the selective hydrodeoxygenation (HDO) of 2,6-dimethoxy-1,4-benzoquinone (DMBQ) to 1,4-cyclohexanediol (CHDO) in neat water. Using a wet-chemical approach, ultra-small ruthenium (Ru) nanoclusters were precisely engineered onto rod-shaped CeO₂ supports. The resulting Ru/CeO₂ catalyst, with a low Ru loading of ~0.97 wt%, achieves an unprecedented CHDO yield of 96.7% at 200°C and 2 MPa H₂, significantly outperforming current benchmarks involving organic solvents. Advanced characterizations (AC-HAADF-STEM and XAFS) reveal that strong metal-support interactions (SMSI) stabilize the Ru nanoclusters and generate abundant interfacial oxygen vacancies. These sites work synergistically to activate C–O bonds, facilitating a kinetically preferred "deoxygenation-before-saturation" pathway that suppresses over-hydrogenated byproducts. This study not only overcomes the limitations of poor solubility and low selectivity in aqueous systems but also provides atomic-level insights into designing cluster-based catalysts for complex biomass transformations.