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Mechanistic Study of Ethanol Dehydrogenation over Silica‐Supported Silver

2013; Wiley; Volume: 5; Issue: 8 Linguagem: Inglês

10.1002/cctc.201300033

1867-3899

Vitaly L. Sushkevich, І. І. Іванова, Esben Taarning,

Oxidative Organic Chemistry Reactions

Abstract A silica‐supported Ag catalyst has been shown to be an efficient heterogeneous catalyst for the oxidant‐free dehydrogenation of ethanol into acetaldehyde. The reaction mechanism has been investigated by in situ FTIR spectroscopy. The kinetic isotope effects for proton and hydride abstraction have been studied by using CH 3 CD 2 OH and CH 3 CH 2 OD as labeled reactants. The results indicate that OH bond activation and the formation of a hydrogen‐bonded complex take place on the silica support and that the Ag particles are necessary for the activation of the CH bond. The kinetic isotope effect ( k H / k D ) is 1.9 for CH 3 CD 2 OH and 1.8 for CH 3 CH 2 OD. The concerted mechanism of CH cleavage on the Ag sites and proton abstraction on the silica sites is proposed to account for the results of the spectroscopic and kinetic experiments.