EFFECTS OF LOCAL REACTANT CONCENTRATION PERTURBATIONS IN OSCILLATORY CATALYSIS

Reaction-rate oscillations in CO oxidation over heterogeneous platinum thin-film catalysts were studied at atmospheric pressure where spatia l coupling is due to gas-phase diffusion of reactant concentration gra dients. The catalyst was perturbed locally by the introduction of CO d irectly above the surface, while the resulting spatiotemporal behavior was monitored using infrared imaging. The transient response of the s ystem was studied in both the steady-state and oscillatory regimes, an d comparisons are made between the observed behavior and predictions f rom models for the oscillations. Using these perturbations, global beh avior was initiated using a localized effect. Similarities and differe nces between the induced oscillations and those occurring naturally ar e discussed, as are tests to vary the phase of the oscillatory cycle. (C) 1998 American Institute of Physics. [S0021-9606(98)00613-8].