On the metal–support synergy for selective gas-phase ethanol oxidation over MgCuCr2O4 supported metal nanoparticle catalysts

• The nature of metal influences the synergy of M/MgCuCr2O4 in ethanol oxidation.
• Pt and Pd are more active and less selective due to facile C–C bond cleavage.
• Cu and Ag are prone to oxidation and thus render low activity.
• Stable Au0–Cu+ synergy is the most efficient for acetaldehyde production.
• Decreasing Au loading and increasing Au dispersion enhance Au0–Cu+ synergy.

Achieving high yields in the production of bulk chemicals is an important goal for the chemical industry. We investigated the influence of the metal on the catalytic performance of M/MgCuCr2O4 (M = Cu, Ag, Pd, Pt, Au) catalysts to better understand the metal–support synergy for the aerobic oxidation of ethanol. Pt/MgCuCr2O4 and Pd/MgCuCr2O4 are more active and less selective for ethanol oxidation than the other catalysts, mainly because they can dehydrogenate and then cleave the carbon–carbon bonds in ethanol at relatively low temperature. Because of the facile oxidation of Cu0 and Ag0 under aerobic oxidation conditions, Cu/MgCuCr2O4 and Ag/MgCuCr2O4 are less active for ethanol oxidation. On contrary, Au/MgCuCr2O4 is a very active, selective and stable catalyst for sustainable production of acetaldehyde, achieving 96% selectivity at full ethanol conversion (space–time–yield up to 583 galdehyde gAu−1 h−1) at 250 °C. Low gold loading and high gold dispersion are important to enhance the Au0–Cu+ synergy and the catalytic efficiency of Au/MgCuCr2O4.

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