Structural stability of kinetic models: Anomalies due to irreversible adsorption

Authors

  • Rob H. Nibbelke,

    1. Schuit Institute of Catalysis, Laboratorium voor Chemische Technologie, Eindhoven University of Technology, 5600 MB, Eindhoven, The Netherlands
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  • Jozef H. B. J. Hoebink,

    Corresponding author
    1. Schuit Institute of Catalysis, Laboratorium voor Chemische Technologie, Eindhoven University of Technology, 5600 MB, Eindhoven, The Netherlands
    • Schuit Institute of Catalysis, Laboratorium voor Chemische Technologie, Eindhoven University of Technology, 5600 MB, Eindhoven, The Netherlands
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  • Mart H. J. M. de Croon,

    1. Schuit Institute of Catalysis, Laboratorium voor Chemische Technologie, Eindhoven University of Technology, 5600 MB, Eindhoven, The Netherlands
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  • Guy B. Marin

    1. Schuit Institute of Catalysis, Laboratorium voor Chemische Technologie, Eindhoven University of Technology, 5600 MB, Eindhoven, The Netherlands
    Current affiliation:
    1. Universiteit Gent, Laboratorium voor Petro-chemische Techniek, Krijgslaan 281, B-9000, Gent, Belgium
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Abstract

The assumption of irreversible adsorption of a reactant can lead to a structurally unstable kinetic model. The structural instability is caused by the fact that two steadystate solutions intersect in the bifurcation diagram o j for example, the degree of surface coverage of one of the adsorbates us. the partial pressure of one of the reactants. One of the two solutions is a trivial solution, corresponding to a catalyst surface completely covered with the irreversibly adsorbing reactant. The intersection point is a transcritical bifurcation point. A structurally stable kinetic model is obtained i f an arbitrarily small desorption rate coefficient is introduced. Two examples are discussed in which a transcritical bifurcation point is encountered, that is, the total oxidation of ethene in three-way catalysis and the chemical vapor deposition of refractory metals. The consequences of the existence of a transcritical bifurcation point for kinetic parameter estimation and reactor simulation are emphasized.

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