A Robust Method for the Estimation of Kinetic Parameters for Systems Including Slow and Rapid Reactions—From Differential-Algebraic Model to Differential Model

Dmitry Murzin,Johan Wärnå,Jyri-Pekka Mikkola,Esko Tirronen,Tapio Salmi,Valerie Eta

doi:10.3390/pr8121552

Dmitry Murzin, Johan Wärnå + Show 4 more

Open Access

https://doi.org/10.3390/pr8121552

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Journal: Processes	Publication Date: Nov 27, 2020
Citations: 1	License type: CC BY 4.0

Affiliation: Åbo Akademi University, Umeå University

Abstract

Reliable estimation of kinetic parameters in chemical systems comprising both slow and rapid reaction steps and rapidly reacting intermediate species is a difficult differential-algebraic problem. Consequently, any conventional approach easily leads to serious convergence and stability problems during the parameter estimation. A robust method is proposed to surmount this dilemma: the system of ordinary differential equations and nonlinear algebraic equations is converted to ordinary differential equations, which are solved in-situ during the parameter estimation. The approach was illustrated with two generic examples and an example from green chemistry: synthesis of dimethyl carbonate from carbon dioxide and methanol.

Highlights

A reliable estimation of kinetic and thermodynamic parameters is one of the most important tasks in chemical reaction engineering
Order surmount the numerical aproblems demanding task when coupled to a parameter estimation task
In order to surmount the numerical often appearing for differential-algebraic equations (DAE) systems, we propose a robust procedure, which implies the problems often of appearing for DAE

Summary

Introduction

A reliable estimation of kinetic and thermodynamic parameters is one of the most important tasks in chemical reaction engineering. Like in the case of some homogeneous gas-phase reactions, is it possible to determine the kinetic constants a priori, exclusively from theoretical calculations. In most cases, an extensive matrix of experimental work is needed. In the presence of heterogeneous catalysts, small variations in the chemical composition and physical structure of the catalyst can change the reaction kinetics, and a new experimental program is inevitable. Kinetic experiments are carried out in batch reactors or in continuous reactors with a well-established flow pattern, i.e., perfect back-mixing or plug flow. The kinetic and thermodynamic parameters are determined by non-linear regression analysis.

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