Kinetic study of the “surface explosion” phenomenon in the NO+CO reaction on Pt(100) through dynamic Monte Carlo simulation

Abstract

The extremely narrow production peak of N2 and CO2 which occurs in the reaction of NO+CO on Pt(100), a phenomenon known as "surface explosion," is studied using a dynamic Monte Carlo method on a square lattice at low pressure under isothermal conditions. This analysis incorporates recent experimental evidence obtained for the same reaction on a Rh(111) surface, which has shown that N2 production occurs either from the classical N+N recombination step or by the formation and successive decay of a (N-NO)* intermediary species. Moreover, the NO dissociation rate is inhibited by coadsorbed NO and CO molecules and is enhanced both by the presence of empty sites and adsorbed N atoms as nearest neighbors. These effects are taken into account in this study, along with the experimental adsorption, desorption, and diffusion rates of the reactants. The "explosive" phenomenon is analyzed through the evolution over time of an adsorbed NO+CO monolayer at a fixed temperature of 400 K. Furthermore, as the diffusion processes of the adsorbates are included, cellular structures are observed. Our simulations show quantitative agreement in the position of maxima with those obtained through experiments using isothermal desorption mass spectroscopy.