Highly Efficient Hydrodeoxygenation of Guaiacol over Boron-Doped Porous Biochar-Encapsulated Co Nanocatalysts under Mild Conditions

The selective hydrodeoxygenation (HDO) of guaiacol to cyclohexanol shows significant promise for biomass valorization, although achieving high yields remains a key challenge. In this study, a series of boron-doped biochar-encapsulated Co nanocatalysts were prepared and applied in HDO of guaiacol to cyclohexanol. It was found that boron doping promotes the formation of carbon defects and electron-deficient Co. Specifically, the strong metal–support interaction between defect-rich carbon and Co nanoparticles not only promoted the dispersion of Co nanoparticles but also facilitated the reduction of cobalt oxide, thereby significantly enhancing HDO activity. Furthermore, boron-coordinated cobalt centers (denoted as Co–B/C) acted as Lewis acid sites, which promoted the selective activation and cleavage of etheric CAr-OCH3 bonds while preserving aliphatic C–OH bonds. In situ DRIFTS and reaction kinetics revealed that selective adsorption and activation of the etheric CAr-OCH3 bond to form a phenol intermediate are crucial for achieving high selectivity to cyclohexanol. DFT calculations further confirmed that boron doping creates electron-deficient Co species, which preferentially cleave the CAr-OCH3 bond and lower its activation barrier. Under 160 °C and 2 MPa conditions, [email protected] gives the best catalytic performance, achieving 100% guaiacol conversion and 97.4% selectivity to cyclohexanol. This work presents a sustainable and effective strategy for the selective conversion of guaiacol to cyclohexanol, demonstrating broad application in the HDO of lignin-derived compounds.