Response of Catalyst Surface Concentrations to Forced Concentration Oscillations in the Gas Phase. The NO, CO, O<sub>2</sub> System over Pt-Alumina

Hegedus, L. Louis; Chang, C.; McEwen, D. J.; Sloan, Elaine M.

doi:10.1021/i160076a008

Cited by 41 publications

(11 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Using Monte Carlo simulations they found that this surface model presents the main features of the pure CO-O 2 system, which contains an active phase where the carbon dioxide molecules are produced continuously. After the appearance of this article, an avalanche of other papers concerning the reaction catalytic surfaces also have appeared in the literature [4][5][6][7][8][9][10][11][12][13][14][15]. In general, these papers are related with the own ZGB model or they are extensions of the same, concerning the various aspects of the experimental observations of these phenomena.…”

Section: Introductionmentioning

confidence: 96%

Dimer Production in a Poisoned Catalytic Model

Schmidt

Santos

2001

phys. stat. sol. (a)

View full text Add to dashboard Cite

We studied a catalytic reaction model among three monomers on a square lattice using Monte Carlo simulations. Our model consists in the introduction of an irreversible adsorption step to the well known Ziff, Gulari, and Barshad model. In this step, the third monomer blocks one site on the catalytic surface. Besides, we also allow for the diffusion of the monomers on the surface. This model does not present a phase transition, because the steady states are always poisoned for any value of the adsorption rate of the monomers. However, we have determined the total dimer production rate and the mean lifetime of the catalytic surface as a function of the adsorption rate of the monomers. We have seen that the total production of dimers and the mean lifetime exhibit a maximum value in different values of the adsorption rates of the monomers. This result is independent of the diffusion rate. However, we also noted that the production rate of dimers decreases and the mean lifetime increases when the diffusion process is dominant.

show abstract

Section: Introductionmentioning

confidence: 96%

Dimer Production in a Poisoned Catalytic Model

Schmidt

Santos

2001

phys. stat. sol. (a)

View full text Add to dashboard Cite

show abstract

“…Several experiments show that it is possible to increase the efficiency of catalytic reactions by subjecting the system to periodic external forcing [5,6,7,8,9]. Monte Carlo simulations of the Ziff, Gulari, and Barshad (ZGB) model without desorption [13] indicate that an enhancement of the catalytic activity is observed when the system is perturbed by a periodic force that drives it briefly into the CO poisoned state [13,14].…”

Section: Introductionmentioning

confidence: 99%

Response of a catalytic reaction to periodic variation of the CO pressure: IncreasedCO2production and dynamic phase transition

et al. 2005

View full text Add to dashboard Cite

We present a kinetic Monte Carlo study of the dynamical response of a Ziff-Gulari-Barshad model for CO oxidation with CO desorption to periodic variation of the CO pressure. We use a square-wave periodic pressure variation with parameters that can be tuned to enhance the catalytic activity. We produce evidence that, below a critical value of the desorption rate, the driven system undergoes a dynamic phase transition between a CO 2 productive phase and a nonproductive one at a critical value of the period and waveform of the pressure oscillation. At the dynamic phase transition the period-averaged CO 2 production rate is significantly increased and can be used as a dynamic order parameter. We perform a finite-size scaling analysis that indicates the existence of power-law singularities for the order parameter and its fluctuations, yielding estimated critical exponent ratios β/ν ≈ 0.12 and γ/ν ≈ 1.77. These exponent ratios, together with theoretical symmetry arguments and numerical data for the fourth-order cumulant associated with the transition, give reasonable support for the hypothesis that the observed nonequilibrium dynamic phase transition is in the same universality class as the two-dimensional equilibrium Ising model.

show abstract

“…Positive results were in fact reported in a number of studies conducted typically under atmospheric pressure conditions [6][7][8][9][10]. Under these conditions mass and heat transfer plays a dominant role contrary to the low pressure ( p < 10 −3 mbar) single crystal experiments in which periodic forcing was also investigated.…”

Section: Introductionmentioning

confidence: 90%

“…Non-stationary reaction conditions may im-prove the yield and selectivity of reactions or reduce energy consumption as compared to stationary conditions [4][5][6]. oxidation of CO and unburned hydrocarbons as well as NO reduction [6][7][8][9][10]. In heterogeneous catalysis experimental studies with periodic forcing focused on the reactions of the automotive catalytic converter, i.e.…”

Section: Introductionmentioning

confidence: 99%

Periodic Forcing of NO Reduction on a Pt(100) Surface

Schütz¹,

Imbihl²

2002

Zeitschrift Für Physikalische Chemie

View full text Add to dashboard Cite

The influence of a cycled gas feed on reactions of the automotive catalytic converter has been investigated under low pressure conditions ( p < 10 −3 mbar) with a Pt(100) surface as catalyst. Catalytic NO reduction with CO or H 2 as reducing agent was studied in binary mixtures. The reactions were forced around the unstable high rate branch of the rate vs. T hysteresis by applying a square-wave modulation of p CO ( p H2 ). For the NO + CO reaction the yield vs frequency dependence exhibits a pronounced maximum. The pressure modulation causes a periodic structural transformation 1 × 1 ↔ hex. The frequency dependence of the yield is largely related to the average concentration of defects which are created during the phase transition.

show abstract

Response of Catalyst Surface Concentrations to Forced Concentration Oscillations in the Gas Phase. The NO, CO, O₂ System over Pt-Alumina

Abstract: 80 cm3/(g s) will have a very small (e < 0.025) effect on

Cited by 41 publications

References 7 publications

Dimer Production in a Poisoned Catalytic Model

Dimer Production in a Poisoned Catalytic Model

Response of a catalytic reaction to periodic variation of the CO pressure: IncreasedCO2production and dynamic phase transition

Periodic Forcing of NO Reduction on a Pt(100) Surface

Contact Info

Product

Resources

About

Response of Catalyst Surface Concentrations to Forced Concentration Oscillations in the Gas Phase. The NO, CO, O2 System over Pt-Alumina

Abstract: 80 cm3/(g s) will have a very small (e < 0.025) effect on

Cited by 41 publications

References 7 publications

Dimer Production in a Poisoned Catalytic Model

Dimer Production in a Poisoned Catalytic Model

Response of a catalytic reaction to periodic variation of the CO pressure: IncreasedCO2production and dynamic phase transition

Periodic Forcing of NO Reduction on a Pt(100) Surface

Contact Info

Product

Resources

About

Response of Catalyst Surface Concentrations to Forced Concentration Oscillations in the Gas Phase. The NO, CO, O₂ System over Pt-Alumina