THE ELUCIDATION OF THE KINETICS AND MECHANISMS OF THE CATALYTIC OXIDATION OF TRACE AMOUNTS OF DIMETHYL ETHER IN OXYGEN BY TRANSIENT PHENOMENA

Thermal desorption experiments with different heating schemes were used to study the kinetics and mechanisms of the catalytic oxidation of dimethyl ether (DME) on supported Pt catalysts. The experimental apparatuses were fully automated by using a microcomputer control system. This made possible direct evaluations of several key kinetic parameters as well as long-term evaluations of the catalysts. The oxidation of DME catalyzed by Pt/SiO₂-Al₂O₃, catalyst has been shown to involve the chemisorption of DME on the support and the chemisorption of oxygen on Pt metal sites. The surface reaction between chemisorbed DME and oxygen was found to be the rate-determining step under the experimental conditions investigated. The proposed reaction mechanism using the kinetic parameters estimated from the thermal desorption experiments predicts the experimental results very well. Acetylene was found to have a promotional effect for the reaction. It is believed that carbon from acetylene plays a key role in this reaction enhancement.