Gold Catalyst Anchored to Pre-Reduced Co3O4 Nanorods for the Hydrodeoxygenation of Vanillin Using Alcohols as Hydrogen Donors

The preparation of highly dispersed metal catalysts with strong electronic metal-support interactions (EMSIs) is of great significance. In this study, oxygen vacancies (OVs) were generated on the surfaces of Co3O4 nanorods (NRs) through NaBH4 treatment, and then the generated surface OVs were used to anchor gold clusters. The resulting catalyst was used for the hydrodeoxygenation (HDO) of vanillin based on transfer hydrogenation with alcohol donors. The conversion of vanillin and the selectivity to 2-methoxy-4-methylphenol (MMP) both reached 99% under the optimized reaction conditions, and these values were significantly higher than those obtained for the gold catalyst supported on the untreated Co3O4 NRs. The obtained results were verified by theoretical calculations and experimental data and confirmed the existence of strong EMSIs between the OV-enriched Co3O4 NRs (Co3O4 NRs-OVs) and the gold clusters, which allows electron transfer from the Co3O4 NRs to gold. Increasing the number of electrons on the gold surface can promote the catalytic hydrogen transfer of alcohol, in addition to selectively adsorbing the C=O group in vanillin to improve the selectivity toward MMP. This strategy based on the OV-anchoring of metals onto the surface of a support can be extended to other metals, thereby providing a promising method for the design of advanced and highly efficient metal catalysts.