Catalytic combustion of dry carbon monoxide by external power activation

The catalytic combustion of dry carbon monoxide and air in a planar stagnat ion-point flow over a platinum foil with external power is studied in this paper. The reduced heterogeneous kinetics are modelled with the dissociativ e adsorption of the molecular oxygen and the non-dissociative adsorption of CO, together with a surface reaction of the Langmuir-Hinshelwood type and the desorption reaction of the adsorbed product, CO2(s). The resulting gove rning equations have been numerically integrated and the whole S-shaped res ponse curve has been obtained as a function of the mixture initial concentr ation. The critical conditions for the catalytic ignition and extinction ar e deduced using high activation energy asymptotics of the desorption kineti cs of the most efficient adsorbed reactant, CO(s). We obtained a very good agreement between the numerical and asymptotic results for the ignition and extinction conditions. In general, the ignition process can be well modell ed without reactant consumption, while extinction occurs in the partial dif fusion-controlled regime, with a finite non-zero concentration of carbon mo noxide close to the plate. (C) 2000 Published by Elsevier Science B.V. All rights reserved.