Significant Promotion of Carboxyl Groups in Palladium Nanoparticles-Supported Biomass Carbon Catalysts for Efficient Low-Temperature Hydrodeoxygenation of Lignin Derivatives in Water

Selective and efficient low-temperature hydrodeoxygenation (HDO) of lignin derivatives in water for the production of valuable biofuel and chemicals is still challenging. Herein, we reported biomass carbon-supported ultrafine Pd nanoparticles as highly active and stable catalysts for low-temperature HDO of vanillin (a typical lignin-derived compound) to 2-methoxy-4-methylphenol (MMP). We found that the abundant carboxyl groups on the resultant catalyst greatly accelerated the conversion of the generated intermediate (vanillyl alcohol, VAL), and then, the synergistic catalysis between carboxyl groups and Pd nanoparticles promoted the efficient production MMP through a free-radical pathway. Other lignin derivatives with different functional groups were also efficiently converted to the corresponding products over the prepared catalyst. This work may provide a new idea for designing a biomass-derived catalyst for efficient transformation of various lignin derivatives to produce value-added biofuels and chemicals.