Spectroscopic Characterization of Surface Oxygen Species on Barium-Containing Methane Coupling Catalysts
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Promotion of MgO, CaO, and ZnO with 2 mol% Ba imparts high activity and C2 selectivity to these oxide supports for the oxidative coupling of CH4 at 800-850°C. X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD) of CO2 have been employed to characterize the nature of surface species on both the fresh and used catalysts. These techniques have established that a direct correlation exists between the oxidative coupling activity of these promoted oxides and their ability to form surface peroxide ions (O22) in the presence of gaseous O2, but that activity is not directly related to support basicity. Selective poisoning of CH4/CD4 isotopic exchange reactions indicate that at least two different types of sites that are capable of activating C-H bonds in CH4 exist on these catalysts. © 1994 Elsevier Science B.V.
author list (cited authors)
Rosynek, M. P., Dissanayake, D., & Lunsford, J. H.