A comparative study of alcohol oxidation over nanoporous gold in gas and liquid phase

The aerobic oxidation of methanol and ethanol in liquid phase is investigated using unsupported nanoporous gold (npAu) catalysts and compared to gas phase experiments. We pursue the question if this material is still suited as a type of model catalyst even under much more complex conditions in liquid phase. Indeed, npAu is an active catalyst for both liquid and gas phase oxidation of methanol and ethanol with O2 under mild conditions (starting at 40 °C). While in case of methanol solely the self coupling product (methyl formate) is detected, the more facile formation of the acetaldehyde in case of ethanol results in the formation of the free aldehyde (acetaldehyde) and the coupling product (ethyl acetate) in similar amounts. To further probe the surface chemistry, cross coupling reactions between both alcohols, as well as the acetaldehyde are performed. As observed also in gas phase experiments, the formation of the surface bonded aldehyde by β-H elimination of the alcoxy species is rate determining.

Subjects

Alcohols

Gold

Heterogeneous catalysis

Mesoporous materials

DDC Class

530: Physik

600: Technik

Funding(s)

FOR 2213: Teilprojekt "Gefügeentwicklung und Auswirkungen der Mechanik auf die Katalyse"

More Funding Information

Supported in the context of an Interregio Research Unit by Deutsche Forschungsgemeinschaft (DFG-FOR2213, Subprojects 2, 3 and 6).

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A comparative study of alcohol oxidation over nanoporous gold in gas and liquid phase