One of the important challenges in the field of catalysis is identification of the mechanism of the reaction as it occurs on the surface of the catalyst. Knowledge of the reaction mechanism is sought in order to identify the elementary processes that govern the overall activity of the catalyst and its selectivity to desired products and the relationship of these processes to the properties of the catalyst. The desired information can be obtained from experiments aimed identifying reaction intermediate and the dynamics of their formation and consumption, and the way in which these dynamics relate to the overall reaction kinetics. Additional information can be gathered from theoretical studies aimed at estimating the free energy landscape on which the reaction occurs and its relationship to the composition and structure of the catalytically active center. This talk will examine how to analyze the free energy landscape using the energy-span approach developed by Kozuch and Shaik (Acc. Chem. Res. 2011, 44, 101) in order to define the overall turnover frequency predicted from the free-energy calculations. It will also be shown under what circumstances this analysis can identify the rate-determining step. Another issue addressed is defining the conditions under which analysis of the reaction enthalpy landscape is sufficient to correctly identify the rare-determining step. Finally, the identification of selectivity-determining step will be discussed.

Identifying the rate- and selectivity-determining steps for heterogeneously catalyzed reactions

2019 Spring National Meeting

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