Fluctuations in kinetic oscillations on nm-sized catalyst particles

Abstract

For adsorption–desorption equilibrium at nm-sized supported catalyst particles, the fluctuations of the number of adsorbates are given by the grand canonical distribution. To clarify what may happen far from equilibrium during chemical oscillations on such particles, we have executed Monte Carlo simulations of the kinetics of CO oxidation accompanied by the formation of surface oxide. The fluctuations were analyzed locally, i.e. inside each oscillation period, and globally by comparing the coverages at different oscillation periods. In both cases, the fluctuations are found to often deviate from those corresponding to equilibrium. In particular, the locally defined fluctuations depend on the phase and may be nearly equal to and/or appreciably larger or smaller than those at equilibrium.