Extracting meaningful standard enthalpies and entropies of activation for surface reactions from kinetic rates

Peter J. Doyle; Aditya Savara; Stephen S. Raiman

doi:10.1007/s11144-020-01747-2

Extracting meaningful standard enthalpies and entropies of activation for surface reactions from kinetic rates

Peter J. Doyle, Aditya Savara, Stephen S. Raiman

Nuclear Fuel Element Performance

Research output: Contribution to journal › Article › peer-review

9 Scopus citations

Abstract

While analyses based on the Arrhenius kinetic model have been successfully applied since its introduction, the Arrhenius model neglects to describe pre-exponential factor in a scientifically meaningful fashion. Since the 1930s, transition-state theory (TST), has met with success in interpreting the pre-exponential factor’s value, allowing a standard entropy of activation to be estimated. However, analyses based on TST’s assumptions have been applied inconsistently in the literature, particularly in corrosion science, leading to difficulty in comparison of standard entropy of activations from different studies. In this work, the foundational principles of TST and standard states are discussed and a standard method to apply TST in analyzing rates of surface reactions is recommended. When full details are not available, reacting species’ concentrations should be normalized to the concentration of active surface sites. For corrosion reactions, conversion relationships are given to convert from units of corrosion rate to surface reaction rate, consistent with TST. This method is dubbed a surface reactant equi-density approximation. Application of this standard to reported data results in adjustments of the standard entropy of activation between − 65 and +50 J/mol K and brings reported entropies into a narrower range of values.

Original language	English
Pages (from-to)	551-581
Number of pages	31
Journal	Reaction Kinetics, Mechanisms and Catalysis
Volume	129
Issue number	2
DOIs	https://doi.org/10.1007/s11144-020-01747-2
State	Published - Apr 1 2020

Funding

Thanks to John Stahl for his assistance in this work. This work was supported by the U.S. Department of Energy, Office of Nuclear Energy, Advanced Fuels Campaign (P.J.D and S.S.R) and supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division (A.S.). This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow other to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). Thanks to John Stahl for his assistance in this work. This work was supported by the U.S. Department of Energy, Office of Nuclear Energy, Advanced Fuels Campaign (P.J.D and S.S.R) and supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division (A.S.). This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow other to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ).

Funders	Funder number
Advanced Fuels Campaign
DOE Public Access Plan
Office of Basic Energy Sciences
United States Government
U.S. Department of Energy
Office of Science
Office of Nuclear Energy
Chemical Sciences, Geosciences, and Biosciences Division	DE-AC05-00OR22725

Keywords

Activated complex theory
Standard entropy of activation
Standard state
Surface reactions
Theory of absolute reaction rates
Transition state theory

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10.1007/s11144-020-01747-2

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title = "Extracting meaningful standard enthalpies and entropies of activation for surface reactions from kinetic rates",

abstract = "While analyses based on the Arrhenius kinetic model have been successfully applied since its introduction, the Arrhenius model neglects to describe pre-exponential factor in a scientifically meaningful fashion. Since the 1930s, transition-state theory (TST), has met with success in interpreting the pre-exponential factor{\textquoteright}s value, allowing a standard entropy of activation to be estimated. However, analyses based on TST{\textquoteright}s assumptions have been applied inconsistently in the literature, particularly in corrosion science, leading to difficulty in comparison of standard entropy of activations from different studies. In this work, the foundational principles of TST and standard states are discussed and a standard method to apply TST in analyzing rates of surface reactions is recommended. When full details are not available, reacting species{\textquoteright} concentrations should be normalized to the concentration of active surface sites. For corrosion reactions, conversion relationships are given to convert from units of corrosion rate to surface reaction rate, consistent with TST. This method is dubbed a surface reactant equi-density approximation. Application of this standard to reported data results in adjustments of the standard entropy of activation between − 65 and +50 J/mol K and brings reported entropies into a narrower range of values.",

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Extracting meaningful standard enthalpies and entropies of activation for surface reactions from kinetic rates

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