• DOI:10.1126/science.1195055
• Corpus ID: 18483488

Reactivity of the Gold/Water Interface During Selective Oxidation Catalysis

@article{Zope2010ReactivityOT,
  title={Reactivity of the Gold/Water Interface During Selective Oxidation Catalysis},
  author={Bhushan N. Zope and David D. Hibbitts and Matthew Neurock and Robert J. Davis},
  journal={Science},
  year={2010},
  volume={330},
  pages={74 - 78}
}

• Bhushan N. Zope, D. Hibbitts, +1 author R. Davis
• Published 1 October 2010
• Chemistry
• Science

Indirect Oxidation by Oxygen Partial oxidation of alcohols to aldehydes and ketones must avoid complete oxidation to carbon dioxide and water. Zope et al. (p. 74) examined the partial oxidation of ethanol and glycerol to acids in alkaline aqueous solvents over gold and platinum catalysts. Conversions were highest for gold supported on titania, but studies with isotopically labeled molecular oxygen showed that oxygen incorporated into the acid comes from hydroxide ions. Direct incorporation of oxygen did not occur even for the platinum catalysts, despite the fact that oxygen can dissociate on this metal. Instead, molecular oxygen appeared to regenerate hydroxide ions at the metal surface through the formation of peroxide intermediates. Hydroxide at the metal/liquid interface promotes the catalytic activity of gold during the partial oxidation of alcohols. The selective oxidation of alcohols in aqueous phase over supported metal catalysts is facilitated by high-pH conditions. We have studied the mechanism of ethanol and glycerol oxidation to acids over various supported gold and platinum catalysts. Labeling experiments with 18O2 and H218O demonstrate that oxygen atoms originating from hydroxide ions instead of molecular oxygen are incorporated into the alcohol during the oxidation reaction. Density functional theory calculations suggest that the reaction path involves both solution-mediated and metal-catalyzed elementary steps. Molecular oxygen is proposed to participate in the catalytic cycle not by dissociation to atomic oxygen but by regenerating hydroxide ions formed via the catalytic decomposition of a peroxide intermediate.