Insight into the Au/CoAlOx Catalyst with Spinel Structure for Efficient Oxidation of Benzyl Alcohol

Selective oxidation of benzyl alcohol to benzaldehyde is crucial for sustainable chemical synthesis, which provides the atom-economical and environmentally benign pathways. In this work, we used the in situ reduction immobilization to synthesize a series of Au nanoparticles supported by CoAlOx support with spinel structure for alkali-free oxidation of benzyl alcohol. The synthesis methodology was preliminarily optimized and the influence of Co/Al molar ratio in Au/CoAlOx on the catalytic performances was subsequently revealed based on characterizations. Results suggested that the electronic interaction between Au and CoAlOx can be regulated and maximized under the Co/Al ratio of 3. It became a main factor to modulate the dispersion of Au nanoparticles, surface chemical composition, as well as the oxygen adsorption/activation ability. Benefiting from such synergistic interaction, the optimized Au/Co3AlOx catalyst achieved 86.1% BnOH conversion under 99.9% benzaldehyde selectivity with well-maintained structural stability under recycle tests. This work provides a rational design strategy for developing highly efficient gold catalysts with well-constructed Au-support interfaces for the alkali-free oxidation of alcohol.