Kinetic oscillations in the catalytic CO oxidation on Pt(100): Theory

Imbihl, R.; Cox, MacGregor; Ertl, G.; Müller, Helmut; Brenig, Wilhelm

doi:10.1063/1.449834

Cited by 248 publications

(100 citation statements)

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“…[3,4] By "global" we mean oscillations in concentrations of adsorbed species or P t substrate states averaged over the entire crystal surface or, in experiments, some macroscopic region of the surface. The principal features that give rise to such oscillations, which involve coupling between surface phase transformations and the oxidation kinetics, were elucidated in earlier studies [4][5][6][7] and are as follows: The surface-catalysed CO oxidation occurs by a Langmuir-Hinshelwood mechanism [8]:…”

Section: Introductionmentioning

confidence: 99%

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Surface structure and catalytic CO oxidation oscillations

Danielak

Perera²,

Moreau³

et al. 1996

Physica A: Statistical Mechanics and its Applications

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A cellular automaton model is used to describe the dynamics of the catalytic oxidation of CO on a P t(100) surface. The cellular automaton rules account for the structural phase transformations of the P t substrate, the reaction kinetics of the adsorbed phase and diffusion of adsorbed species. The model is used to explore the spatial structure that underlies the global oscillations observed in some parameter regimes. The spatiotemporal dynamics varies significantly within the oscillatory regime and depends on the harmonic or relaxational character of the global oscillations. Diffusion of adsorbed CO plays an important role in the synchronization of the patterns on the substrate and this effect is also studied.

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Section: Introductionmentioning

confidence: 99%

“…[4][5][6][7] The nature of the wave propagation processes depends on both the type of global oscillation and the diffusion coefficient of adsorbed CO, D CO . We investigate the spatial structure that underlies the global oscillations.…”

Section: Introductionmentioning

confidence: 99%

Surface structure and catalytic CO oxidation oscillations

Danielak

Perera²,

Moreau³

et al. 1996

Physica A: Statistical Mechanics and its Applications

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“…The basic model for the CO-oxidation kinetics on Pt͑100͒ was developed by Imbihl et al 5 One must specify the fraction, 1ϫ1 , of the substrate in the 1ϫ1-state, so then a fraction hex ϭ1Ϫ 1ϫ1 is in the hex-state. CO can adsorb on both 1ϫ1-and hex-regions, so local coverages, CO 1ϫ1 and CO hex , are specified for each region.…”

Section: Model For Co-oxidation On Pt(100)mentioning

confidence: 99%

“…4 In this contribution, we consider exclusively COoxidation on Pt͑100͒. 5 An important feature of this system is that the clean Pt͑100͒ surface undergoes a ''hex''-reconstruction, but significant local coverages of CO ͑or O͒ lift this hex-reconstruction to recover a 1ϫ1-structure. 6 In analyzing spatio-temporal behavior in this reaction system, one should regard the highly mobile CO as diffusing in a ''disordered environment.''…”

Section: Introductionmentioning

confidence: 99%

Percolative diffusion of CO during CO oxidation on Pt(100)

Tammaro

Evans

1996

The Journal of Chemical Physics

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During CO-oxidation on Pt(100), CO diffuses in a "disordered environment" produced by a complex pattern of reconstructed and unreconstructed regions of the substrate. Macroscopic diffusion of CO is effectively only possible on percolating 1X1-regions of the substrate. We treat the spatio-temporal behavior observed in this reaction system accounting in the simple way for the percolative nature of CO-diffusion. This is done via incorporation into the reaction-diffusion equations of a suitable chemical diffusion coefficient, exploiting ideas from the theory of transport in disordered media. We use these equations to analyze the propagation of reactive, O-rich pulses into a CO-covered 1X1-background. Disciplines Mathematics | Physics CommentsThe following article appeared in Journal of Chemical Physics 104,9 (1996) During CO-oxidation on Pt͑100͒, CO diffuses in a ''disordered environment'' produced by a complex pattern of reconstructed and unreconstructed regions of the substrate. Macroscopic diffusion of CO is effectively only possible on percolating 1ϫ1-regions of the substrate. We treat the spatio-temporal behavior observed in this reaction system accounting in the simple way for the percolative nature of CO-diffusion. This is done via incorporation into the reaction-diffusion equations of a suitable chemical diffusion coefficient, exploiting ideas from the theory of transport in disordered media. We use these equations to analyze the propagation of reactive, O-rich pulses into a CO-covered 1ϫ1-background.

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“…The kinetic mechanism for this reaction is well established and has been modelled extensively [7][8][9]. Spatial modelling has concentrated on Pt{110} using a simplified representation of the kinetic mechanism, extended to include diffusion terms (and sometimes gas global coupling) [10].…”

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confidence: 99%

Pattern Formation during the Oxidation of CO onPt{100}: A Mesoscopic Model

et al. 2007

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Constantly changing irregular patterns of carbon monoxide (CO) and oxygen are seen during CO oxidation on platinum crystals in the [100] orientation. Ours is the first reaction-diffusion model to reproduce this pattern formation on physically feasible length and time scales, faithfully incorporating the available experimental data. Numerical simulations show patterns made up of CO and oxygen fronts moving at similar speeds to those seen in experiments [4][5][6].PACS numbers: 68.43. Bc,68.47.De,82.40.Ck Spatiotemporal pattern formation occurs in a number of catalytic reactions, such as the Belousov-Zhabotinsky reaction where oscillating spirals and targets are seen [1]. Similar structures form during the catalytic oxidation of carbon monoxide on the surface of single platinum crystals, where patterns comprise areas of different surface phase or covered by different adsorbates. During the reaction oxygen and CO are adsorbed onto the platinum surface. At high enough temperatures and for certain orientations of the surface relative to the bulk crystal, the presence of adsorbates leads to a phase change, i.e. a rearrangement of the surface platinum atoms. When the oxygen and CO react, carbon dioxide gas is released and the surface reverts to its original configuration. This cycle can lead to kinetic oscillations in the surface phase. If communication between different areas on the crystal is very rapid compared with the rate of oscillation, the whole surface oscillates in phase; otherwise there can be phase lags across the surface and spatial patterns arise [2]. There are two main spatial coupling mechanisms: diffusion of CO across the surface, important at low pressures, and global coupling through the gas phase, which dominates at high pressures. The surface orientation has a decisive effect on pattern formation: in the [111] orientation there is no phase change and hence no patterns, on Pt{110} classical spirals and targets are seen (e.g. [3]), while on Pt{100} the patterns are typically more irregular [4-6], though circular wavefronts are also seen [5].In this Letter, we model pattern formation in CO oxidation on a single platinum crystal in the [100] orientation. The kinetic mechanism for this reaction is well established and has been modelled extensively [7][8][9]. Spatial modelling has concentrated on Pt{110} using a simplified representation of the kinetic mechanism, extended to include diffusion terms (and sometimes gas global coupling) [10]. These models produce results that qualitatively resemble experimentally observed patterns, but they cannot be used for detailed quantitative comparison since both the kinetic and diffusion mechanisms are simplified. Monte Carlo methods are also used, but at present these must assume unrealistically low diffusion coefficients in order to allow pattern formation on computationally accessible length and time scales [11]. We present a mesoscopic spatial model based on the detailed kinetic mechanism [9] together with diffusion terms derived from a careful consideration of...

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Kinetic oscillations in the catalytic CO oxidation on Pt(100): Theory

Cited by 248 publications

References 48 publications

Surface structure and catalytic CO oxidation oscillations

Surface structure and catalytic CO oxidation oscillations

Percolative diffusion of CO during CO oxidation on Pt(100)

Pattern Formation during the Oxidation of CO onPt{100}: A Mesoscopic Model

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