LATTICE-GAS MODEL MIMICKING THE NO+CO REACTION ON PT(100)

Various NO-reduction reactions on Pt(100) exhibit similar dynamical be havior, presumably due to an empty site requirement for NO dissociatio n. This motivates analysis of a lattice-gas model which incorporates t his feature, and which here is chosen to mimic the NO+CO reaction on P t(100): both reactants adsorb at single empty sites, NO instantaneousl y dissociates given an adjacent empty site and nitrogen adatoms thus f ormed are immediately removed), and adjacent CO and O instantaneously react. We also include desorption of adsorbed NO and CO, but no adspec ies diffusion. At lower temperatures where desorption is absent, we sh ow that poisoning occurs with the reaction rate decreasing as R(CO2) s imilar to e(-kt), where k>0 except for equal reactant adsorption rates . The introduction of desorption produces reactive steady states, and (in different regimes) nonequilibrium poisoning transitions, critical points, and transitions to bistability.