Response of a model of CO oxidation with CO desorption and diffusion to a periodic external CO pressure

Abstract

We present a study of the dynamical behavior of a Ziff-Gulari-Barshad model with CO desorption and lateral diffusion. Depending on the values of the desorption and diffusion parameters, the system presents a discontinuous phase transition between low and high CO coverage phases. We calculate several points on the coexistence curve between these phases. Inclusion of the diffusion term produces a significant increase in the CO 2 production rate. We further applied a square-wave periodic pressure variation of the partial CO pressure with parameters that can be tuned to modify the catalytic activity. Contrary to the diffusion-free case, this driven system does not present a further enhancement of the catalytic activity, beyond the increase induced by the diffusion under constant CO pressure.

Model for the catalytic oxidation of CO, including gas-phase impurities and CO desorption

“…(Experimental evidence indicates that the desorption rate of oxygen is negligible [29].) Hysteresis is then observed as y varies close to y 2 , which now becomes a function of the desorption rate [40][41][42]. In the present paper we study the effects of this CO desorption process on our previous model for CO oxidation with inert impurities in the gas phase and next-nearest-neighbor adsorption of oxygen atoms [12].…”

Conjugate field and fluctuation-dissipation relation for the dynamic phase transition in the two-dimensional kinetic Ising model

“…These include mean-field studies of domainwall motion in an anisotropic XY model in one dimension [12,13,14], KMC simulations of a three-dimensional Ising system [15], and KMC simulations of a uniaxially anisotropic Heisenberg system in an off-axial field [16], an elliptically polarized applied field [17], and with the effect of a thin-film surface energy [18,19,20]. The phenomenon has also been observed in simulations of CO oxidation under oscillating CO pressure [21,22]. Further simulation studies of the DPT in the two-dimensional kinetic Ising model have appeared [23,24,25,26,27], as well as analytical studies of the DPT [28,29,30,31].…”

CO oxidation on stepped single crystal electrodes: A dynamic Monte Carlo study

“…In this case, adsorption of OH at ''special'' sites, usually defects or steps, nucleates the reaction after which it proceeds only at the interface between the reacting species, causing the formation and growth of islands [18]. Recent investigations of the effects of surface diffusion in a simple Langmuir-Hinshelwood model for CO oxidation can be found in the work of Machado et al [19][20][21]. Also note that in the presence of (strong) lateral interactions, rapid surface diffusion may not lead to mixing and mean-field behavior [22].…”