Kinetics of Methane Catalytic Combustion on Mn-Substituted Barium Hexaaluminate Catalysts

摘要

The oxidation of methane has been studied in the temperature range 475 deg C <= T <= 660 deg C isothermally using Mn-substituted barium hexaaluminate catalysts. The solid material was characterized by BET, XRD and TPD of oxyge. Reproducible oxidation rates provided and the effects of varying both methane (3.8-18.8 Torr) and oxygen (22.8-114 Torr) partial pressure at various reaction temperatures are presented to generate experimental databases. The suitability of several kinetic expressions, which is based on reaction mechanisms that have been advanced in the literature to represent the experimental data was assessed. On the whole, several mechanistic models provided an adequate fit to the entire experimental data sets. Appreciable deviations of the predicted from the actual reaction rates have allowed us to discriminate between the various mechanistic models. The best description was obtained for a model featuring a two-step reaction sequence on a nonuniform surface.