Acidic O dopants collaborating with oxidized Pd centers to promote hydrodeoxygenation of vanillin

Hydrodeoxygenation is the key technology for realizing the conversion of biomass into high value-added chemicals, but usually encounters low efficiency and harsh conditions due to the rich electron density and strong C-O bonds of O-containing groups. Herein, an efficient catalyst is precisely constructed with abundant acidic O dopants and well-exposed oxidized Pd centers for hydrodeoxygenation of vanillin. Through a tannic acid-assisted strategy, it is precisely constructed on alumina that electron-deficient O species doped as ether types in carbon along with ultra-small PdO nanoparticles. The collaboration of acidic sites from O dopants and oxidized Pd centers on PdO boosts hydrodeoxygenation of vanillin into valuable 2-methoxy-4-methylphenol in 99 % yield with a turnover frequency value of 752 h −1 under mild conditions (80 °C, 0.5 MPa H 2 ), significantly surpassing similar catalysts without oxidized Pd centers or O dopants as well as commercial Pd heterogeneous and homogeneous catalysts. Further theoretical calculations disclose that oxidized Pd centers are superior to metallic Pd centers for hydrogenating vanillin aldehyde group, which is revealed to stabilize the reaction system and facilitate the adsorption of H 2 , while the acidic O dopants play a crucial role in promoting the subsequent alcohol-based deoxygenation process by facilitating the C-O bond cleavage synergistically.