Structural changes to Fe3+ cationic species in Fe-exchanged zeolite BEA during the selective catalytic reduction (SCR) of NOx with NH3 were probed by UV-vis spectroscopy. The distribution between Fe2+ and Fe3+ species was characterized by IR spectroscopy of adsorbed CO. Upon heating to 723 K, some of the Fe cations formed Fe-O-Fe bonds that underwent reversible structural transformation under NH3-SCR conditions. The in situ formed Fe oxide clusters could be dissociated to isolated Fe cations at 423 K, while at higher temperatures O-bridged Fe clusters were again formed. The structure of the Fe cluster is related to the Al distribution in the zeolite probed by Co2+ ion exchange. We propose here that two Fe cations bound within one six-membered ring containing an Al pair form hydroxylated dimeric Fe-O-Fe in the zeolite. This was supported by a structure simulation of a binuclear [HO-Fe(III)-O-Fe(III)-OH] model.     «

Structural changes to Fe3+ cationic species in Fe-exchanged zeolite BEA during the selective catalytic reduction (SCR) of NOx with NH3 were probed by UV-vis spectroscopy. The distribution between Fe2+ and Fe3+ species was characterized by IR spectroscopy of adsorbed CO. Upon heating to 723 K, some of the Fe cations formed Fe-O-Fe bonds that underwent reversible structural transformation under NH3-SCR conditions. The in situ formed Fe oxide clusters could be dissociated to isolated Fe cations at...     »

ISI Document Delivery No.: 076BZ Times Cited: 0 Cited Reference Count: 42 Kim, Jeongnam Jentys, Andreas Maier, Sarah M. Lercher, Johannes A. Jentys, Andreas/D-4622-2009 Jentys, Andreas/0000-0001-5877-5042 Bayerisches Staatsministerium fur Wissenschaft, Forschung und Kunst This project was funded by the Bayerisches Staatsministerium fur Wissenschaft, Forschung und Kunst. The authors would like to thank Martin Neukamm for AAS measurements, Monica Pop for assistance in in situ UV-vis measurements, and Stefanie Reiner for her contribution to low-temperature CO adsorption measurements. 0 Amer chemical soc Washington     «

ISI Document Delivery No.: 076BZ Times Cited: 0 Cited Reference Count: 42 Kim, Jeongnam Jentys, Andreas Maier, Sarah M. Lercher, Johannes A. Jentys, Andreas/D-4622-2009 Jentys, Andreas/0000-0001-5877-5042 Bayerisches Staatsministerium fur Wissenschaft, Forschung und Kunst This project was funded by the Bayerisches Staatsministerium fur Wissenschaft, Forschung und Kunst. The authors would like to thank Martin Neukamm for AAS measurements, Monica Pop for assistance in in situ UV-vis measurements,...     »