Improving the selectivity of hydrogenation and hydrodeoxygenation for vanillin by using vacancy-coupled Ru–N3 single atoms immobilized on defective boron nitride

Abstract

The coordination and geometric engineering of SACs will provide a novel approach to advanced catalysts for energy related applications. Hexagonal boron nitride (h-BN) is a stable graphene-like material with a high specific surface area and is expected to be an excellent support for single atom catalysts (SACs). The regulatory mechanism of isolated metal active sites on the h-BN matrix is still ambiguous, including the significance of the defect effect. Herein, we report a neoteric ruthenium single-site catalyst supported on vacancy-affluent porous h-BN, where Ru is coordinated with three nitrogen atoms (Ru-SA/pBN-V_N) for selective vanillin conversion reactions with high efficiency. X-ray absorption fine structure (XAFS) results based on synchrotron radiation and density functional theory (DFT) calculations suggest that the nitrogen vacancy adjacent to the active Ru–N₃ center has a strong atomic interface regulation effect. Derived from the remarkable metal–support interaction, Ru-SA/pBN-V_N shows excellent conversion (∼100%) and selectivity (∼100%) in temperature-dependent hydrogenation (obtaining vanillyl alcohol at 60 °C) and hydrodeoxygenation (gaining 2-methoxy-p-cresol at 120 °C) reactions of vanillin, also with superb catalytic stability. We propose an innovative perspective that the strongly coupled metal–ligand moiety with an adjacent vacancy may play synergistic roles in heterogeneous catalysis.