Promoting Effect of Copper Doping on LaMO3 (M = Mn, Fe, Co, Ni) Perovskite-Supported Gold Catalysts for Selective Gas-Phase Ethanol Oxidation

Developing more effective gold–support synergy is essential for enhancing the catalytic performance of supported gold nanoparticles (AuNPs) in the gas-phase oxidation of ethanol to acetaldehyde (AC) at lower temperatures. This study demonstrates a significantly improved Au–support synergy achieved by copper doping in LaMO3 (M = Mn, Fe, Co, Ni) perovskites. Among the various Au/LaMCuO3 catalysts, Au/LaMnCuO3 exhibited exceptional catalytic activity, achieving an AC yield of up to 91% and the highest space-time yield of 764 gAC gAu−1 h−1 at 225 °C. Notably, this catalyst showed excellent hydrothermal stability, maintaining performance for at least 100 h without significant deactivation when fed with 50% aqueous ethanol. Comprehensive characterization reveals that Cu doping facilitates the formation of surface oxygen vacancies on the Au/LaMCuO3 catalysts and enhances Au–support interactions. The LaMnCuO3 perovskite stabilizes the crucial Cu+ species, resulting in a stable Au-Mn-Cu synergy within the Au/LaMnCuO3 catalyst, which facilitates the activation of O2 and ethanol at lower temperatures. The optimization of the reaction conditions further improves AC productivity. Kinetic studies indicate that the cleavages of both the O-H bond and the α-C-H bond of ethanol are the rate-controlling steps.