Determination of pre-exponential factor and reaction mechanism in a model-free way

The effective activation energy (Eα) dependency is used to compute the dependence of the pre-exponential factor (Aα) and of the mathematical function that describe the reaction mechanism f(α) in a model-free way. The effective rate constant kα(T) depends on both temperature (T) and extent of convers...

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Bibliographic Details
Published in:Thermochimica acta Vol. 691; p. 178707
Main Author: Sbirrazzuoli, Nicolas
Format: Journal Article
Language:English
Published: Elsevier B.V 01.09.2020
Elsevier
Subjects:
activation energy
Chemical Sciences
Isoconversional kinetic analysis
Model-free kinetics
Nonisothermal kinetics
Pre-exponential factor
Reaction mechanism
reaction mechanisms
temperature
Isoconversional kinetic analysis
Reaction mechanism
Pre-exponential factor
Nonisothermal kinetics
Model-free kinetics
ISSN:0040-6031, 1872-762X
Online Access:Get full text
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Summary:The effective activation energy (Eα) dependency is used to compute the dependence of the pre-exponential factor (Aα) and of the mathematical function that describe the reaction mechanism f(α) in a model-free way. The effective rate constant kα(T) depends on both temperature (T) and extent of conversion (α) for multi-step reactions in nonisothermal mode. [Display omitted] •Three methods to compute the pre-exponential factor in a model-free way are proposed.•Four methods to compute the function that describes the reaction model in a model-free way are proposed.•Accurate results were obtained using the compensation effect in association with Friedman’s or Vyazovkin’s methods.•Accuracies were estimated using a simulated multi-step reaction mechanism. Four methods to compute the pre-exponential factor and the mathematical function that describe the reaction mechanism in a model-free way are proposed and their accuracies were estimated using a complex (multi-step) reaction mechanism that has been simulated. It is shown that the use of the compensation effect in association with Friedman’s or Vyazovkin’s isoconversional methods gives accurate results. Model-free estimation of these parameters can be an efficient tool for the elucidation of complex reaction mechanisms, in complementarity to the estimation of the effective activation energy dependency with temperature and extent of conversion.
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ISSN:0040-6031
1872-762X
DOI:10.1016/j.tca.2020.178707