Model discrimination in oscillatory CO oxidation on platinum catalysts at atmospheric pressure

Reaction-rate oscillations in CO oxidation on platinum catalysts at atmospheric pressure are believed to depend on a mechanism which blocks adsorption by the reactants. Two proposed models, the oxidation–reduction and carbon models, explain the oscillations based on different site-blocking chemical species, and both describe the observed phenomena relatively well. A series of tests is described which was designed to use the differences between these models in order to determine which model best describes the observed behavior. In these tests, a platinum thin-film catalyst is first exposed to only one of the reactants. The second reactant is then added, and the transient response of the system is measured. From this test, it is found that while neither model predicts completely the initial transients, the oxidation–reduction model agrees best with the experimental results. The transient behavior from these tests and its implications are discussed.