Low temperature gas-phase oxidation of ethanol over Au/TiO2

A set of nanostructured gold catalysts with Au loadings ranging from 0.5 to 7.0 wt% on a TiO2 support was prepared and evaluated in a gas-phase oxidation of ethanol with molecular oxygen. The catalytic activity was measured in a flow reactor under atmospheric pressure using temperature programmed heating. The catalysts with Au loadings varying from 2 wt% to 7 wt% displayed two distinct temperature dependent peaks of catalytic activity in ethanol oxidation to acetaldehyde. The temperature, at which the first peak occurred, 125 °C, is extraordinarily low for the gas-phase oxidation of ethanol. In contrast, gold supported on Al2O3 and SiO2, which was prepared and tested in the same reaction for the purpose of comparison, showed conventional, steady increase of ethanol conversion at temperatures above 200 °C. The results demonstrated a possibility to employ Au/TiO2 catalysts in selective low temperature gas phase oxidation of ethanol. The probable reasons of the unusual catalytic behavior of Au/TiO2 are discussed.

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► Au/TiO2 catalysts with Au loadings ranging from 0.5 to 7.0 wt% are prepared.
► Gas-phase aerobic oxidation of ethanol is catalyzed by Au/TiO2 to give acetaldehyde.
► The catalytic activity occurred at extraordinarily low temperature, around 125 °C.
► The mechanistic aspects of the unusual catalytic behavior of Au/TiO2 are discussed.