Characterization of Fe-exchanged BEA zeolite under NH3 selective catalytic reduction conditions

Jeongnam Kim, Andreas Jentys, Sarah M. Maier, Johannes A. Lercher

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

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.

Original languageEnglish
Pages (from-to)986-993
Number of pages8
JournalJournal of Physical Chemistry C
Volume117
Issue number2
DOIs
StatePublished - 17 Jan 2013

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