New insight in the platinum-catalyzed CO oxidation kinetic mechanism by using an advanced TAP

The platinum-catalyzed oxidation of carbon monoxide was studied using a new fast transient technique, referred to as Multitrack, to evaluate the possibilities of this technique and to investigate the reaction mechanism. The experiments indicate that the reaction takes place according to the Langmuir-Hinshelwood model. From experiments performed using oxygen-18 isotope, it was shown that the desorption of carbon dioxide produced at the platinum surface is a kinetically relevant step influencing the reaction rate. Although the Multitrack technique, and other TAP-like techniques, are used in general to evaluate fast reactions. It was shown that when performing transient experiments with high reaction rates the surface composition can vary through the position of the catalyst in the bed, as sequential gas pulses show a moving reaction front-like behavior. This behavior can cause pulse responses having more than one maximum in a pulse experiment, which is often erroneously attributed to multiple surface reactions. (C) 1997 Elsevier Science B.V.