Kinetic oscillations in the catalytic CO oxidation on Pt(100): Theory

Abstract

Experimental investigations on the catalytic oxidation of CO on well‐defined Pt(100) surfaces at low pressures (∼10⁻⁴ Torr) revealed under certain conditions the occurrence of kinetic oscillations which were associated with periodic transformations of the surface structure propagating wave‐like across the surface area. Based on experimental information about the various elementary steps involved (adsorption, desorption, surface reaction, adsorbate‐induced surface structural transformation) a set of coupled differential equations describing the kinetics of the various processes was established. A simplified version of these equations allows analytical treatment and provides qualitative insight into the occurrence of oscillations through linear stability analysis. Numerical solution of the full set of reaction‐diffusion equations reproduces the essential spatio‐temporal features of the experimental observations, although full quantitative agreement would still require better adjustment of the parameters involved as well as further refinement of the model.