A quantitative analysis of transient kinetic experiments: The oxidation of CO by O2 over Pt Original Research Article

Transient kinetic experiments allow to assess quantitatively the rate coefficients of individual elementary steps. Experiments were performed in the temperature range 300–400 K with temporal analysis of products (TAP) for CO oxidation over polycrystalline platinum, initially fully precovered with O adatoms, at varying degrees of CO and O coverage. Experimental evidence for the existence of islands was found. The results were described with an island model, that accounts for CO chemisorption from a precursor state, followed by either CO incorporation into CO islands or by a surface reaction with O adatoms from adjacent O islands. CO chemisorption was not activated and its rate coefficient was estimated as 40 s−1, while the surface reaction was relatively fast. Indications for the size of the CO and O islands were found.