The Development of a Model for the Cooperative Behavior of Palladium Crystallites During the Catalytic Oxidation of CO

Jaeger, N. I.; Möller, Karin; Plath, P

doi:10.1002/bbpc.19850890613

Cited by 15 publications

(2 citation statements)

References 21 publications

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“…In most cases, the reaction exhibits very strange timeseries with selfsimilar patterns of conversion break downs. Cellular automata models have been developed to describe qualitatively the self-af®ne temporal patterns [3,9,10,20,21]. Cellular automata models have been developed to describe qualitatively the self-af®ne temporal patterns [3,9,10,20,21].…”

Section: Introductionmentioning

confidence: 99%

A New Discrete Model for the Non-Isothermic Dynamics of the Exothermic CO-Oxidation on Palladium Supported Catalyst

Ballandis¹,

Plath²

2001

Journal of Non-Equilibrium Thermodynamics

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The oxidation of CO on a palladium support catalyst under normal pressure in a continuous¯ow reactor was observed. For experimental work an X type zeolite loaded with 0.5 weight % palladium was used as catalyst. The palladium salt was inserted into the zeolite by ion exchange and then reduced under hydrogen¯ow. Palladium particles with an average diameter of 4 nm were formed under these conditions. The conversion rate shows a dynamic behaviour with selfaf®ne pattern of excursions to a smaller conversion rate on a time scale of some seconds. The in¯uence of the¯ow rate upon the dynamics of the CO conversion pattern was studied. Increasing¯ow rate causes increasing of frequency of maximum excursions, increasing of smaller excursions, increasing of complexity of the pattern and decreasing of maximum conversion (base line).The system was simulated by a time and space discrete automaton. The model is a considerable extension of that described by Liauw et al. [7]. For example, in the extended model the temperature of palladium particles (non-isothermic conditions), the¯ow rate and the distribution of particle size is introduced. The temperatures of the palladium particles have an important in¯uence upon the velocities of reaction, oxidation and reduction. Arrhenius equations were used to describe the in¯uence of temperature. To obtain self-af®ne patterns, the coupling of oscillators with very different frequencies are necessary. These were obtained by different self-organised`operating temperatures' of the palladium particles in the active state. During the catalytic oxidation of CO, the heat production and the heat loss for each model palladium particle equilibrate very fast and a temporary maximum`operating temperature' occurs for each of them. This operating temperature of each model palladium particle depends upon the size of each particle.

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Section: Introductionmentioning

confidence: 99%

A New Discrete Model for the Non-Isothermic Dynamics of the Exothermic CO-Oxidation on Palladium Supported Catalyst

Ballandis¹,

Plath²

2001

Journal of Non-Equilibrium Thermodynamics

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“…The temperature dependence of the temporal structure of the process can be modelled qualitatively by a one-dimensional automaton, as introduced in ref. (15) and (16). To understand why it is possible to describe the complex dynamics of this catalytic system simply in this manner one has to reflect on the fact that the cooperative effect is arranged by an excitation wave travelling along the two-dimensional network of Pd particles in the catalyst supported on the silver sieve or ceramic support.…”

Section: Discussionmentioning

confidence: 96%

Cooperative effects in heterogeneous catalysis. Part 2.—Analysis and modelling of the temperature dependence of the oscillating catalytic oxidation of CO on a palladium Al2O3-supported catalyst

Plath¹,

Möller²,

Jaeger³

1988

J. Chem. Soc., Faraday Trans. 1

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Ein diskretes mathematisches Modell für die Dynamik der Methanoloxidation an einem Palladium‐Trägerkatalysator

Gerhardt

Schuster

Plath

1986

Ber Bunsenges Phys Chem

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The Development of a Model for the Cooperative Behavior of Palladium Crystallites During the Catalytic Oxidation of CO

Cited by 15 publications

References 21 publications

A New Discrete Model for the Non-Isothermic Dynamics of the Exothermic CO-Oxidation on Palladium Supported Catalyst

A New Discrete Model for the Non-Isothermic Dynamics of the Exothermic CO-Oxidation on Palladium Supported Catalyst

Cooperative effects in heterogeneous catalysis. Part 2.—Analysis and modelling of the temperature dependence of the oscillating catalytic oxidation of CO on a palladium Al2O3-supported catalyst

Ein diskretes mathematisches Modell für die Dynamik der Methanoloxidation an einem Palladium‐Trägerkatalysator

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