Methane Oxidation over Palladium: On the Mechanism in Fuel-Rich Mixtures at High Temperatures

Abstract

A kinetic modeling study on methane oxidation over reduced Pd for various fuel-rich conditions around the stoichiometric point of the partial oxidation at high temperatures (900–1100 K) is presented. A thermodynamically consistent detailed surface reaction mechanism is developed within the mean field approximation. The proposed kinetic model consists of 54 elementary-step based reactions including seven gas-phase species and 15 surface intermediates. Three different methane activation paths are implemented, comprising pyrolytic C–H bond dissociation steps, oxygen-assisted and dual-oxygen-assisted CH4 activation. In situ experimental measurements in a quasi-autothermally operated flow reactor, using the capillary sampling technique, are performed for model evaluation. The provided experimental data includes spatially resolved temperature and concentration profiles within a single catalytic channel of a Pd/Al2O3-coated monolith. Supplementary numerical simulations based on literature data for fuel-lean and fuel-rich conditions at high temperatures extend the model’s capability to predict a wide range of different experimental conditions.