The catalytic activity of supported gold nanoparticles has been studied extensively, but fundamental reaction kinetics and mechanisms, the nature of support effects, and the role of water are not always well understood.  We studied benzyl alcohol oxidation as a probe reaction for these important factors, performing differential reaction kinetics and Arrhenius studies.  For both Au/alumina and Au/titania catalysts, the reaction dependence on benzyl alcohol show saturation kinetics; consequently, the data was examined with a kinetic treatment comparable to a Michaelis-Menten analysis.  The analysis included a slightly modified mechanism from the literature, invoking adsorption of the alcohol onto the support, and proton transfer from the alcohol to generate an active alkoxide at the metal-support interface.  The kinetic data was well described by this data, which provided an important framework for considering the differences in activity between the catalysts.  Double reciprocal plots indicated that differences in reactivity could be attributed to fundamental differences in the rate constant for hydride transfer from the benzylic carbon to Au, rather than to differences in the number of active sites.  This conclusion is further supported by intentional poisoning and Hammett studies.

Characterizing the kinetic capabilities of supported gold nanoparticle catalysts using benzyl alcohol oxidation

253rd National Meeting (2017)

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