Mechanistic Classification of Chemical Oscillators and the Role of Species

Eiswirth, M.; Freund, A.; Ross, John

doi:10.1002/9780470141298.ch2

Cited by 57 publications

(45 citation statements)

References 83 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In search of possible generalizations of that problem, Eiswirth et al [41] have proposed its relation to the classification of chemical oscillators. Here we shall focus on the electrochemical systems only.…”

Section: Classification Of Electrochemical Oscillators Based On Impedmentioning

confidence: 99%

Application of Impedance Spectroscopy to Electrochemical Instabilities

Orlik

2012

Monographs in Electrochemistry

View full text Add to dashboard Cite

Electrochemical impedance spectroscopy (EIS), a well-established technique in classical electrochemistry [1], can also be very useful for the analysis of stability of electrochemical systems, including diagnosis of selected bifurcations. Impedance spectra of such dynamical systems allow also classify electrochemical oscillators into respective types. In fact, due to linearization involved in the concept of impedance, this way of the stability analysis of electric (electrochemical) circuits is a specific variant of linear stability analysis described in Sect. 1.3.In this section a short presentation of the principle of impedance measurements is described, in order to make the reader familiar with the notation used further in this chapter. The basis for this summary will be typical (Randles-type) equivalent circuit from Fig. 2.6, in which Z f will henceforth mean generally the ac impedance, measured for ac frequency f [Hz] (or angular frequency o ¼ 2pf [rad s À1 ]). The idea of such equivalent circuits, coming from the seminal work of Randles [2], was concordant with the experimental equipment used in early times of impedance measurements. It involved the ac bridge, in which one branch contained the experimental system, the impedance characteristics of which had to be balanced, in the other branch, by the impedance of the electric (equivalent) circuit, possibly closely reflecting the properties of the experimental one.Typically the electrochemical cell is first brought into steady-state, or at least quasi-steady-state (E ss , I ss ) which is further perturbed with the externally applied small amplitude, sinusoidal ac voltage (typically) or ac current. As a consequence, the electrode potential E and the current I will oscillate around their steady-state values with the same frequency o, but in general case exhibiting (frequency dependent) phase difference. In general notation one can denote the phase shifts for both the electrode potential and the current as ' 1 and ' 2 , respectively, and then:M. Orlik, Self-Organization in Electrochemical Systems I, Monographs in Electrochemistry,

show abstract

Section: Classification Of Electrochemical Oscillators Based On Impedmentioning

confidence: 99%

Application of Impedance Spectroscopy to Electrochemical Instabilities

Orlik

2012

Monographs in Electrochemistry

View full text Add to dashboard Cite

show abstract

“…Before it was said that the oxidation of CO forms a subsystem for the HCOOH oxidation at Pt electrode, Strasser et al [26] have elaborated this problem in terms of the stoichiometric network analysis (SNA) [81,82] in which, based on the stoichiometric and kinetic coefficients of a chemical reaction mechanism expressed in the relevant network diagram, one can diagnose the system's ability to exhibit dynamical instability. On such diagrams, the arrows connecting the chemical species symbolize the chemical (pseudo)reactions, while the number of feathers and barbs corresponds to the stoichiometric coefficients in relevant chemical reactions (for the stoichiometric coefficient of the consumed species equal to 1, no feather is drawn at the corresponding reaction arrow).…”

Section: The Oxidation Of Formic Acid As the System Of Two Suboscillamentioning

confidence: 99%

Temporal Instabilities in Anodic Oxidation of Small Molecules/Ions at Solid Electrodes

Orlik

2012

Monographs in Electrochemistry

View full text Add to dashboard Cite

Oscillations and multistability in oxidation processes at solid electrodes are important for several reasons. First, they were reported for species that are (or can appear) important in chemical engineering of fuels, including the fuel cells: hydrogen, carbon monoxide, formaldehyde, formic acid/formate ions, 2-propanol, 1-butanol, hydrazine, or ethylene glycol. It can be useful to know how to avoid instabilities involving these species or, on the contrary, to profit from them. Second, electrooxidation of these molecules exhibits rich variety of nonlinear dynamic behaviors which can be treated in a model way for the sake of generalization. Third, some of these processes, under appropriate conditions, can become a source of spatial or spatiotemporal patterns on electrodes which phenomena only recently gained satisfactory explanation and description. In this chapter, we shall summarize the temporal phenomena associated with the oxidation of the above-mentioned molecules, while pattern formation will be discussed in separate Chap. 2 of volume II.Current research data indicate that such processes should be qualified as electrocatalytic, i.e., the electrode surface is actively engaged in the kinetics of the electron transfer reaction, usually involving the process taking place via the adsorbed intermediate. As in the case of other types of electrochemical oscillators, one can observe the evolution of the understanding of the source of chemical instabilitiesfrom early, sometimes oversimplified explanations oriented exclusively on the properties of the electrode/electrolyte interface toward more recent concepts, involving the analysis of the system's stability in terms of nonlinear dynamics. In particular, oscillations under galvanostatic conditions could be understood only recently in terms of the concept of the HN-NDR oscillator [1] (cf. Chap. 3).The anodic oxidation of H 2 on Pt electrode is an electrocatalytic process, in which the electron transfer is preceded by the adsorption of H 2 molecule on the active surface site. Hence, the oscillatory course of this process can be associated M. Orlik, Self-Organization in Electrochemical Systems I, Monographs in Electrochemistry,

show abstract

“…The objective, is to provide guidelines to the user to determine the size of reaction network from the available data. The usual approach dedicated to the determination of reaction networks relies on the linearisation of the dynamics around a reference solution (Eiswirth et al, 1991;Chevalier et al, 1993) and identification of the local Jacobian matrix. Here, in the spirit of (Chen and Bastin, 1996;Bernard and Bastin, 2005), we exploit the structure of the bioprocess (equation (1)) and our arguments do not rely on any linearisation.…”

Section: Introductionmentioning

confidence: 99%

Can we assess the model complexity for a bioprocess: theory and example of the anaerobic digestion process

Bernard

Chachuat

Hélias

et al. 2006

Water Science and Technology

View full text Add to dashboard Cite

In this paper we propose a methodology to determine the structure of the pseudo-stoichiometric coefficient matrix K in a mass balance based model, i.e. the maximal number of biomasses that must be taken into account to reproduce an available data set. It consists in estimating the number of reactions that must be taken into account to represent the main mass transfer within the bioreactor. This provides the dimension of K. The method is applied to data from an anaerobic digestion process and shows that even a model including a single biomass is sufficient. Then we apply the same method to the "synthetic data" issued from the complex ADM1 model, showing that the main model features can be obtained with 2 biomasses.

show abstract

Mechanistic Classification of Chemical Oscillators and the Role of Species

Cited by 57 publications

References 83 publications

Application of Impedance Spectroscopy to Electrochemical Instabilities

Application of Impedance Spectroscopy to Electrochemical Instabilities

Temporal Instabilities in Anodic Oxidation of Small Molecules/Ions at Solid Electrodes

Can we assess the model complexity for a bioprocess: theory and example of the anaerobic digestion process

Contact Info

Product

Resources

About