Influence of the support in aqueous phase oxidation of ethanol on gold/metal oxide catalysts studied by ATR-IR spectroscopy under working conditions

Effects of supports (Co3O4, CeO2, NiO) in the gold-catalyzed aqueous phase oxidation of ethanol (EtOH) to acetic acid (AcOH) were examined. ATR-IR spectroscopy under working conditions of the catalysts uncovered on gold particles bidentate ethoxy, and on supports monodentate ethoxy species, multi-layered ethanol, and acetate. Preferential formation of bidentate ethoxy species and adsorbed EtOH were identified as key factors for high activity and selectivity to AcOH. These requirements were best matched with Au/Co3O4. On NiO, monodentate ethoxy species on the support deteriorated the catalytic performance due to consecutive esterification of AcOH and/or acetate species with EtOH producing undesirable ethyl acetate.

Automated summary

The study found that the formation of bidentate ethoxy species and adsorption of ethanol are key factors for high activity and selectivity in the gold-catalyzed oxidation of ethanol to acetic acid. Co3O4 was identified as the best support material to meet these requirements, while monodentate ethoxy species on NiO deteriorated the catalytic performance.