N2O REDUCTION BY CO OVER AN ALUMINA-SUPPORTED PT CATALYST - FORCED COMPOSITION CYCLING

The reaction dynamics of N2O reduction by CO over an alumina-supported catalyst have been examined using forced square-wave cycling of CO and N2O concentrations. The experiments were carried out using an isothermal recycle reactor operated at 499 K with various values of the cycling frequency and the phase angle between the two composition cycles. Time-average CO conversions as high as five times the steady-state conversion were attained during the forced feed cycling. The observed dynamic behavior of the system has been described by a kinetic model consisting of three elementary steps which incorporates two main features, namely, the adsorbate-induced Pt surface-phase transformation (1 x 1 <-> hex) and the self-exclusion of CO during adsorption on the Pt surface. The model was able to describe quantitatively the experimental results of the steady-state multiplicity behavior of the reaction. Thus, a simple model provides a consistent explanation for both the observed rate enhancement and dynamic CO, response during input cycling and the steady-state multiplicity (C) 1994 Academic Press, Inc.