Effect of CO desorption and coadsorption with O on the phase diagram of a Ziff-Gulari-Barshad model for the catalytic oxidation of CO
TL;DR: The coadsorption step has a profound effect on the transition between the reactive state and the CO-poisoned state, and the coexistence curve between these two states terminates at a critical value k(c) of the desorption rate k, which now depends on p.
Abstract: We study the effect of coadsorption of CO and O on a Ziff-Gulari-Barshad (ZGB) model with CO desorption (ZGB-d) for the reaction CO + O --> CO_2 on a catalytic surface. Coadsorption of CO on a surface site already occupied by an O is introduced by an Eley-Rideal-type mechanism that occurs with probability p, 0 <= p <= 1. We find that, besides the well known effect of eliminating the second-order phase transition between the reactive state and an O-poisoned state, the coadsorption step has a strong effect on the transition between the reactive state and the CO-poisoned state. The coexistence curve between these two states terminates at a critical value k_c of the desorption rate k which now depends on p. Our Monte Carlo simulations and finite-size scale analysis indicate that k_c decreases with increasing values of p. For p=1, there appears to be a sharp phase transition between the two states only for k at(or near) zero.
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01 Jan 2005
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TL;DR: Kinetic Monte Carlo Simulation of Statistical Mechanical Models and Coarse-Grained Mesoscale Descriptions of Catalytic Reaction− Diffusion Processes: 1D Nanoporous and 2D Surface Systems is presented.
Abstract: Traditional mean-field rate equations of chemical kinetics for spatially uniform systems1−3 and the corresponding reaction−diffusion equations describing spatial heterogeneity4−6 have proved immensely useful in elucidating catalytic processes. However, it is well-recognized that standard mean-field rate expressions neglect spatial correlations in the reactant and/or product distribution. It is less well appreciated that the standard treatment of diffusion is generally applicable only at low concentrations and in unrestricted environments. Disciplines Astrophysics and Astronomy | Biological and Chemical Physics | Mathematics | Physics Comments Reprinted (adapted) with permission from Chemical Reviews 115 (2015): 5979,doi:10.1021/cr500453t . Copyright 2015 American Chemical Society. Authors Da-Jiang Liu, Andrés Garcia, Jing Wang, David M. Ackerman, Chi-Jen Wang, and James W. Evans This article is available at Iowa State University Digital Repository: http://lib.dr.iastate.edu/physastro_pubs/176 Kinetic Monte Carlo Simulation of Statistical Mechanical Models and Coarse-Grained Mesoscale Descriptions of Catalytic Reaction− Diffusion Processes: 1D Nanoporous and 2D Surface Systems Da-Jiang Liu,† Andres Garcia,†,‡ Jing Wang,†,§ David M. Ackerman,† Chi-Jen Wang,†,§,# and James W. Evans*,†,‡,§ †Ames LaboratoryUSDOE, Division of Chemical and Biological Sciences, ‡Department of Physics & Astronomy, and Department of Mathematics, Iowa State University, Ames, Iowa 50011, United States
35 citations
TL;DR: In this paper, a modified Ziff-Gulari-Barshad (ZGB) dynamic lattice-gas model for the catalytic oxidation of carbon monoxide (CO) on a surface is presented.
Abstract: We present kinetic Monte Carlo simulations exploring the nonequilibrium phase diagram of a modified Ziff–Gulari–Barshad (ZGB) dynamic lattice-gas model for the catalytic oxidation of carbon monoxide (CO) on a surface. The modified model includes the simultaneous presence of contaminants in the gas phase, CO desorption, CO diffusion, and strong repulsion between adsorbed oxygen (O) atoms; all of which have been observed in experimental systems. We find that the strong O–O repulsion produces higher reaction rates, albeit in a reduced reactive pressure window. In systems with impurities, the CO2 production rate is greatly reduced, but this effect is mitigated by CO desorption and diffusion. CO desorption has the effect of widening the reactive pressure window, while CO diffusion has the effect of increasing the reaction rate. In some parameter regimes the presence of impurities destroys the discontinuous transition between the reactive and high CO coverage phases.
12 citations
Cites background from "Effect of CO desorption and coadsor..."
...Another possibility is an Eley-Rideal mechanism that allows reaction between CO molecules in the gas phase and adsorbed O atoms [20]....
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TL;DR: In this paper, the effect of oscillatory kinetics due to surface reconstructions on Ziff-Gulari-Barshad (ZGB) model discontinuous phase transition was investigated.
Abstract: Using kinetic Monte Carlo simulations, we study the effect of oscillatory kinetics due to surface reconstructions on Ziff-Gulari-Barshad (ZGB) model discontinuous phase transition. To investigate the transition, we do extensive finite size scaling analysis. It is found that the discontinuous transition still exists. On inclusion of desorption in the model, the order-parameter probability distribution broadens but remains bimodal. That is, the first-order phase transition becomes weaker with increase in desorption rate.
8 citations
TL;DR: The Ziff–Gulari–Barshad model is revisited in order to study the behavior of its phase diagram when two well‐known random networks play the role of the catalytic surfaces: the random geometric graph and the Erdös–Rényi network.
Abstract: In this study, we revisited the Ziff-Gulari-Barshad (ZGB) model in order to study the behavior of its phase diagram when two well-known random networks play the role of the catalytic surfaces: the random geometric graph and the Erdos-Renyi network. The connectivity and, therefore, the average number of neighbors of the nodes of these networks can vary according to their control parameters, the neighborhood radius α, and the linking probability p, respectively. In addition, the catalytic reactions of the ZGB model are governed by the parameter y, the adsorption rate of carbon monoxide molecules on the catalytic surface. So, to study the phase diagrams of the model on both random networks, we carried out extensive steady-state Monte Carlo simulations in the space parameters (y, α) and (y, p) and showed that the continuous phase transition is greatly affected by the topological features of the networks while the discontinuous one remains present in the diagram throughout the interval of study.
8 citations
References
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19 Sep 2005TL;DR: A review of Monte Carlo methods of computer simulation can be found in this article, where a brief review of other methods of simulation can also be found, as well as a brief introduction to Monte Carlo studies of biological molecules.
Abstract: Preface 1. Introduction 2. Some necessary background 3. Simple sampling Monte Carlo methods 4. Importance sampling Monte Carlo methods 5. More on importance sampling Monte Carlo methods of lattice systems 6. Off-lattice models 7. Reweighting methods 8. Quantum Monte Carlo methods 9. Monte Carlo renormalization group methods 10. Non-equilibrium and irreversible processes 11. Lattice gauge models: a brief introduction 12. A brief review of other methods of computer simulation 13. Monte Carlo simulations at the periphery of physics and beyond 14. Monte Carlo studies of biological molecules 15. Outlook Appendix Index.
2,055 citations
TL;DR: In this article, the authors studied the distribution function P L ( s ) of the local order parameters in finite blocks of linear dimension L for Ising lattices of dimension d = 2,3 and 4.
Abstract: The distribution function P L ( s ) of the local order parameters in finite blocks of linear dimension L is studied for Ising lattices of dimensionality d = 2,3 and 4. Apart from the case where the block is a subsystem of an infinite lattice, also the distribution in finite systems with free [ P L ( f ) ( s )] and periodic [ P L ( p ) ( s )] boundary conditions is treated. Above the critical point T c , these distributions tend for large L towards the same gaussian distribution centered around zero block magnetization, while below T c these distributions tend towards two gaussians centered at ± M , where M is the spontaneous magnetization appearing in the infinite systems. However, below T c the wings of the distribution at small | s | are distinctly nongaussian, reflecting two-phase coexistence. Hence the distribution functions can be used to obtain the interface tension between ordered phases. At criticality, the distribution functions tend for large L towards scaled universal forms, though dependent on the boundary conditions. These scaling functions are estimated from Monte Carlo simulations. For subsystem-blocks, good agreement with previous renormalization group work of Bruce is obtained. As an application, it is shown that Monte Carlo studies of critical phenomena can be improved in several ways using these distribution functions: ( i ) standard estimates of order parameter, susceptibility, interface tension are improved ( ii ) T c can be estimated independent of critical exponent estimates ( iii ) A Monte Carlo “renormalization group” similar to Nightingale's phenomenological renormalization is proposed, which yields fairly accurate exponent estimates with rather moderate effort ( iv ) Information on coarse-grained hamiltonians can be gained, which is particularly interesting if the method is extended to more general Hamiltonians.
1,259 citations
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13 May 1999TL;DR: In this paper, Driven lattice gases: simulations are used to model the contact process of a lattice gas with a reaction and a contact process with a particle reaction model.
Abstract: Preface 1. Introduction 2. Driven lattice gases: simulations 3. Driven lattice gases: theory 4. Lattice gases with reaction 5. Catalysis models 6. The contact process 7. Models of disorder 8. Conflicting dynamics 9. Particle reaction models Bibliography Index.
1,137 citations
01 May 1999
TL;DR: In this paper, Driven lattice gases: simulations are used to model the contact process of a lattice gas with a reaction and a contact process with a particle reaction model.
Abstract: Preface 1. Introduction 2. Driven lattice gases: simulations 3. Driven lattice gases: theory 4. Lattice gases with reaction 5. Catalysis models 6. The contact process 7. Models of disorder 8. Conflicting dynamics 9. Particle reaction models Bibliography Index.
1,018 citations
TL;DR: In this paper, an irreversible kinetic surface-reaction model based on the reaction of carbon monoxide and oxygen on a catalyst surface was presented, and it was found by computer simulation that the adsorbed molecules on the surface undergo both first-and second-order kinetic phase transitions.
Abstract: An irreversible kinetic surface-reaction model, based upon the reaction of carbon monoxide and oxygen on a catalyst surface, is presented. It is found by computer simulation that the adsorbed molecules on the surface undergo both first- and second-order kinetic phase transitions. These transitions correspond to the "poisoning" phenomenon seen on catalysts. Interesting transient and periodic behavior is also seen.
784 citations