TPD study of NO decomposition on Rh(111) by dynamic Monte Carlo simulation

The kinetics of NO desorption and its decomposition on Rh(111) surfaces have been simulated by using a dynamic Monte Carlo method. During the simulations, we used a triangular lattice that mimics the Rh(111) phase. NO decomposition was studied at low pressure and temperatures ranging from 120 to 1000 K. The present analysis incorporates recent experimental evidence showing that N2 production occurs either from the classical N + N recombination step or by the formation and successive decay of an (N–NO)* intermediate species. Moreover, N2 and NO desorption rates are enhanced and the NO dissociation rate is inhibited by coadsorbed NO, N, and O species as nearest neighbors. These effects are taken into account in this study, along with the experimental adsorption, desorption, dissociation, and diffusion rates of the reactants. Our simulations are consistent with the experimental results of TPD spectra and can explain the formation of two peaks, δ-N2 and β-N2, as a natural consequence of the reaction mechanism herein proposed. Comparisons with different mechanisms used by other authors are also made.