Dynamics of the catalyst deactivation: tutorial experience with formalism of thermodynamics of non-equilibrium processes
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Dynamics of the catalyst deactivation: tutorial experience with formalism of thermodynamics of non‑equilibrium processes V. N. Parmon1,2 · N. M. Ostrovskii3 Received: 19 July 2020 / Accepted: 25 August 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract The catalytic process, during which the catalyst loses activity, is usually difficult for investigation and industrial application, especially when the life time of the catalyst is relatively long (10 to 104 h). Therefore, experimental studies of the deactivation kinetics are very expensive, and mathematical modeling and simulation of the deactivation mechanisms becomes more significant, even more than models of reaction mechanisms. In this paper we present an approach to developing and analysis of deactivation dynamics models based on formalism of thermodynamics of non-equilibrium processes. The simplest two step sequence mechanism of the target reaction is used for deriving and analyzing models of reversible and irreversible deactivation mechanisms corresponding to poisoning and coking phenomena. Differential equations for dynamics of the key deactivation intermediate and of the target reaction rate, as well as of the catalyst relative activity are derived and solved. It is shown that thermodynamic formalism coupled with classic kinetic consideration is useful for the analysis of optimal bond energy of key intermediate with the catalyst, which can provide low deactivation. Keywords Reaction dynamics · Catalyst deactivation · Thermodynamic formalism
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s1114 4-020-01855-z) contains supplementary material, which is available to authorized users. * N. M. Ostrovskii n‑[email protected] 1
Boreskov Institute of Catalysis, Novosibirsk, Russia
2
Novosibirsk State University, Novosibirsk, Russia
3
Euro Gas, Subotica, Serbia
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Reaction Kinetics, Mechanisms and Catalysis
Introduction Deactivation of operating catalysts due to inhibition or irreversible poisoning of their active centers is a typical phenomenon that has a great but often negative effect on the practical use. Of great importance here is the deactivation dynamics which determines, among others, the active lifetime (service cycle) of the catalysts before their regeneration or even change-out. Kinetics of the catalyst deactivation is discussed in numerous original papers, as well as in review papers and monographs [1–6]. The works fulfilled by Levenspiel, Froment, Gavalas, Butt, Wojciechowski in 1960–1970s [1, 7–11] had the greatest impact upon the theory of deactivation processes. In many of these works, semiempirical dependences of the rate of target catalytic reaction (r) on characteristics of the catalyst relative activity (a, 𝜑 ) were suggested. There are two main types of the dependences: 1. Models in terms of the concentration of poison (P) or coke (C, g/g) [7]:
⎧ 1 − 𝛾C ⎪ r = ro 𝜑 (C), 𝜑 (C) = = = ⎨ exp(−𝛾 C) dC ∕ dt = rc ⎪ (1 + 𝛾 C)−1 ⎩
(1)
2. Models in terms of relativ
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