The Formalism of Chemical Thermodynamics Applied to an Oscillatory Multistep Chemical System

Abstract

The thermodynamic optimization of a process focuses on consumption, production, and efficient use of energy. The unsteady-state nature of batch reactor processing requires describing the set of processes’ dynamic behavior for energy optimization. This work aims to apply the formalism of chemical thermodynamics to a multistep chemical system in a batch reactor, aiming for a dynamic description of its evolution to the equilibrium state. As the system of study, we selected a mathematical model called the Oregonator, derived from the mechanism of the oscillating Belousov-Zhabotinsky reaction. In the methodology, we used the reaction quotient to evaluate the Gibbs function, the thermodynamic affinity, and the entropy generation as a function of the reaction extent. The results show that the overall reaction fulfills the thermodynamic fundamentals of chemical equilibrium, despite having a non-stoichiometric coefficient. However, the multistep coupled reaction system does not allow verifying compliance with the thermodynamic foundations of chemical equilibrium. We conclude that it is necessary to improve thermodynamic formalism to describe multistep chemical processes as a function of a global reaction extent variable. In this scenario, the entropy production rate emerges as a promising quantity.