(688e) On the Mechanistic Aspects of Mg6MnO8-Based Redox Catalysts for Oxidative Dehydrogenation of Ethane Via a Chemical Looping Scheme
Previously, we have identified that Mg6MnO8, a mixed oxide with a cation deficient rocksalt structure, is an excellent model redox catalyst for ODH. It is capable of supplying lattice oxygen at rates comparable to the rate of hydrogen formation via thermal cracking of ethane. Unpromoted Mg6MnO8 is highly efficient for deep oxidation of ethane, producing primarily of CO2and water. When promoted with alkali salts, however, it can produce ethylene with exceptional selectivity.
The current work investigates the mechanistic aspects of (promoted) Mg6MnO8 redox catalysts. Extensive characterizations including TPR, TPD, XPS, in-situ XRD, in-situ DRIFTS, Raman Spectroscopy, and pulse reactions are performed. The data indicate that alkali salt promoters induce changes in the bulk and near surface properties of the Mg/MnO system and suppress activation and deep oxidation of ethane and ethylene. Meanwhile, the promoted redox catalysts allow facile combustion of hydrogen, leading to high ethylene yield.