Adsorbed atomic oxygen facilitates the activation of reactants for energy efficient, low temperature reactions of alcohols on gold, such as oxidation and oxidative coupling. Theory indicates that coadsorbed oxgen can also activate C-H bonds in the adsorbed reaction intermediates. We have studied this effect for adsorbed carboxylates. Adsorbed acetate, for example, decomposes at 560K on the clean gold surface, but in the presence of excess oxygen, the decomposition occurs more than 150K lower, near 400K. The oxygen-induced, low temperature decomposition occurs by a completely different mechanism than the high temperature pathway. Using variations in oxygen coverage, acetate coverage, and isotopically labeled reagents, the products and mechanisms have been elucidated for these two decomposition pathways. This principle may apply to reactions of other intermediates important for partial oxidation reactions on gold-based catalysts, with important consequences for reaction selectivity.

Coadsorbed oxygen enables low temperature pathways for reaction intermediates on gold

247th National Meeting (2014)

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