A simulation of oscillatory behavior in the NO+H2 reaction on Pt(100):: effect of diffusion and blocking sites

The catalytic reduction of nitric oxide by H-2 over the Pt(100) surface is studied as a function of partial pressures of the reactants. The mathematical mean field model, originally proposed by Makeev and Nieuwenhuys (J. Chem. Phys. 108 (1998a) 3740) shows kinetic oscillations of the reaction products and near the critical point the dependence of the amplitude of oscillations on the partial pressures ratio p is shown to be very close to that predicted for the Hopf supercritical bifurcation. The model has been extended to include the effect of blocking sites (poisoning) on the catalyst surface. This effect changes the period of the oscillations. Diffusion of the adspecies NO has also been studied and we show in what way it modifies the nonlinear behavior of the kinetic oscillations and the transition to chaos through period-doubling bifurcations. The influence of defects on global coupling as they are increased continuously is also studied. Finally, we use Monte Carlo simulations to show the species distributions and growth as they oscillate in time. (C) 2003 Elsevier Ltd. All rights reserved.