NO-CO surface reaction on a square lattice

Khan, M.A. Majeed; Yaldram, K.; Khalil, G. K.; Khan, K M

doi:10.1103/physreve.50.2156

Cited by 44 publications

(27 citation statements)

References 17 publications

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“…Since this process tends to equalize the sublattice coverages, it is reasonable to expect an active state for sufficiently large values of D N . This is indeed observed in simulations [15,28], where the range ∆ of y values supporting an active state grows steadily with D N . (The PA, as we have noted, yields a similar result in one dimension.)…”

Section: Square Latticesupporting

confidence: 63%

“…But in our theory, the entire range y 1 < y < y 2 becomes active once the diffusion rate D N exceeds a critical value. In simulations the "active window" opens gradually as D N is increased [15,16].…”

Section: Introductionmentioning

confidence: 98%

“…Simulations show the coverages changing rapidly over a narrow range of y, but without discontinuities in the coverages or their slopes.) That the N-sublattice instability is responsible for destroying the active state (despite the absence of global sublattice order), is indicated by the observations that (1) an active state exists in the triangular lattice (which does not admit a decomposition into two sublattices), and (2) that diffusion of N (but not of O, or of CO) restores the possibility of an active state [15,16].…”

Section: Introductionmentioning

confidence: 99%

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Theory of theNO+COsurface-reaction model

et al. 1999

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We derive a pair approximation (PA) for the NO+CO model with instantaneous reactions. For both the triangular and square lattices, the PA, derived here using a simpler approach, yields a phase diagram with an active state for CO-fractions y in the interval y 1 < y < y 2 , with a continuous (discontinuous) phase transition to a poisoned state at y 1 (y 2 ). This is in qualitative agreement with simulation for the triangular lattice, where our theory gives a rather accurate prediction for y 2 . To obtain the correct phase diagram for the square lattice, i.e., no active stationary state, we reformulate the PA using sublattices. The (formerly) active regime is then replaced by a poisoned state with broken symmetry (unequal sublattice coverages), as observed recently by Kortlüke et al. [Chem. Phys. Lett. 275, 85 (1997)]. In contrast with their approach, in which the active state persists, although reduced in extent, we report here the first qualitatively correct theory of the NO+CO model on the square lattice. Surface diffusion of nitrogen can lead to an active state in this case. In one dimension, the PA predicts that diffusion is required for the existence of an active state.

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Section: Square Latticesupporting

confidence: 63%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Theory of theNO+COsurface-reaction model

et al. 1999

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“…In fact, in the former no reactive stationary state has been observed [134,135], as shown in figure 17(a). However, simulation results have shown that diffusion of N (but not of O, or CO) restores the possibility of a reactive state [140,141], as shown in figure 17(b). In fact, in this case a second-order IPT is observed close to P 1CO = 0.203 ± 0.001, while a first-order IPT is found at P 2CO = 0.293 ± 0.001 [141].…”

Section: The Catalytic Reaction Between Nitrogen Monoxide and Carbon mentioning

confidence: 99%

“…However, simulation results have shown that diffusion of N (but not of O, or CO) restores the possibility of a reactive state [140,141], as shown in figure 17(b). In fact, in this case a second-order IPT is observed close to P 1CO = 0.203 ± 0.001, while a first-order IPT is found at P 2CO = 0.293 ± 0.001 [141]. Also, Meng et al [137] have shown that by adding a new reaction channel to YK model (equations (29-32)), such that CO(a) + N(a) → CON(g) + 2S (34) the reactivity of the system becomes enhanced and consequently a reaction window is observed on the square lattice.…”

Section: The Catalytic Reaction Between Nitrogen Monoxide and Carbon mentioning

confidence: 99%

Critical behaviour of irreversible reaction systems

Loscar

Albano

2003

Rep. Prog. Phys.

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An introductory review on the critical behaviour of some irreversible reaction systems is presented. The study of these systems has attracted great attention during the last decades due to, on the one hand, the rich and complex underlying physics, and, on the other, their relevance to numerous technological applications in heterogeneous catalysis, corrosion and coating, development of microelectronic devices, etc. The review focuses on recent advances in the understanding of irreversible phase transitions (IPTs), providing a survey of the theoretical development in the field during the last decade, as well as a detailed discussion of relevant numerical simulations. The Langevin formulation for the treatment of second-order IPTs is discussed. Different Monte Carlo (MC) approaches are also presented in detail and the finite-size-scaling analysis of second-order IPTs is described. Special attention is devoted to the description of the recent progress in the study of first-order IPTs observed upon catalytic oxidation of carbon monoxide and the reduction of nitrogen monoxide, using lattice gas reaction models. Only brief comments are given on other reactions such as the oxidation of hydrogen, ammonia synthesis. Also, a discussion of relevant experiments is presented and measurements are compared with the numerical results. Furthermore, promising areas for further research and open questions are also addressed.

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The effect of inactive impurities on a surface in NO–CO reaction: A Monte Carlo simulation

Ahmad

Baloch

2007

Applied Surface Science

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NO-CO surface reaction on a square lattice

Cited by 44 publications

References 17 publications

Theory of theNO+COsurface-reaction model

Theory of theNO+COsurface-reaction model

Critical behaviour of irreversible reaction systems

The effect of inactive impurities on a surface in NO–CO reaction: A Monte Carlo simulation

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