Bimetallic Au-Pd/α-MoO₃ Catalyst with High Oxygen Vacancies for Selective Oxidation of Cinnamyl Alcohol

Supported Au-Pd nanoparticles (NPs) have been extensively studied in alcohol oxidation reactions. However, few studies use reducible metal oxides as support, which can activate oxygen molecules and boost the selectivity of the reaction. In this work, Au-Pd NPs were supported on α-MoO₃ and evaluated in the selective oxidation of cinnamyl alcohol without solvent. The Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and X-ray photoemission spectroscopy (XPS) analyses showed that the catalyst is richer in oxygen vacancies than the support, being probably responsible for the stability of the NPs (average size 4.62 ± 0.15 nm) and the high conversion and selectivity for the oxidation of cinnamyl alcohol. Furthermore, experiments have shown that the Au:Pd molar ratio influences the catalytic performance and can be optimized by controlling temperature, pressure, and reaction time. The catalyst proved to be active and selective for cinnamaldehyde in short reaction times. It showed satisfactory performance at 30 min and its best activity at 1 h with 94% conversion and 87% selectivity, without loss of activity and selectivity after four runs under the same reaction conditions.

Keywords:
alcohol oxidation; Au-Pd nanoparticles; cinnamyl alcohol; MoO₃