Determination of the Redox Processes in FeBEA Catalysts in NH3-SCR Reaction by Mossbauer and X-ray Absorption Spectroscopy

The nature and oxidation state of iron species in Fe-exchanged BEA zeolites treated in synthetic air or nitrogen were determined by a combination of Mossbauer and X-ray absorption spectroscopy. The linear correlation between the edge energy of the X-ray absorption near edge structure (XANES) and the oxidation state determined by Mossbauer spectroscopy allowed determining the fraction of Fe2+ in situ. The distribution of Fe2+ and Fe3+ in the catalysts depends on the Fe concentration and the conditions of the thermal treatment. It is possible to stabilize isolated Fe2+ cations under ambient atmosphere in the zeolite pores, while FeBEA catalysts show a temperature-dependent oxidation and reduction of the active Fe species during the selective catalytic reduction of nitrogen oxides by NH3 (NH3-SCR), reflecting the equilibrium for NO oxidation.     «

The nature and oxidation state of iron species in Fe-exchanged BEA zeolites treated in synthetic air or nitrogen were determined by a combination of Mossbauer and X-ray absorption spectroscopy. The linear correlation between the edge energy of the X-ray absorption near edge structure (XANES) and the oxidation state determined by Mossbauer spectroscopy allowed determining the fraction of Fe2+ in situ. The distribution of Fe2+ and Fe3+ in the catalysts depends on the Fe concentration and the condi...     »

ISI Document Delivery No.: 761CM Times Cited: 3 Cited Reference Count: 39 Maier, Sarah M. Jentys, Andreas Metwalli, Ezzeldin Mueller-Buschbaum, Peter Lercher, Johannes A. Jentys, Andreas/D-4622-2009 Jentys, Andreas/0000-0001-5877-5042 Bayerisches Staatsministerium fur Wissenschaft, Forschung und Kunst Portions of this research were carried out at the light source facility DORIS III at DESY, Hamburg, Germany. DESY is a member of the Helmholtz Association (HGF). We thank Adam Webb for assistance in using Beamline X1. The authors thank Martin Neukamm for AAS measurements and Prof. Dr. Friedrich Wagner for the fruitful discussion and his help with the Mossbauer measurements. Discussions in the framework of ERIC are gratefully acknowledged. The project was funded by the Bayerisches Staatsministerium fur Wissenschaft, Forschung und Kunst. 4 Amer chemical soc Washington     «

ISI Document Delivery No.: 761CM Times Cited: 3 Cited Reference Count: 39 Maier, Sarah M. Jentys, Andreas Metwalli, Ezzeldin Mueller-Buschbaum, Peter Lercher, Johannes A. Jentys, Andreas/D-4622-2009 Jentys, Andreas/0000-0001-5877-5042 Bayerisches Staatsministerium fur Wissenschaft, Forschung und Kunst Portions of this research were carried out at the light source facility DORIS III at DESY, Hamburg, Germany. DESY is a member of the Helmholtz Association (HGF). We thank Adam Webb for assistance i...     »