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

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

doi:10.1021/jp309277n

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

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

Technical University of Munich

Research output: Contribution to journal › Article › peer-review

39 Scopus citations

Abstract

Structural changes to Fe³⁺ cationic species in Fe-exchanged zeolite BEA during the selective catalytic reduction (SCR) of NO_x 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 language	English
Pages (from-to)	986-993
Number of pages	8
Journal	Journal of Physical Chemistry C
Volume	117
Issue number	2
DOIs	https://doi.org/10.1021/jp309277n
State	Published - 17 Jan 2013

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title = "Characterization of Fe-exchanged BEA zeolite under NH3 selective catalytic reduction conditions",

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.",

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T1 - Characterization of Fe-exchanged BEA zeolite under NH3 selective catalytic reduction conditions

AU - Kim, Jeongnam

AU - Jentys, Andreas

AU - Maier, Sarah M.

AU - Lercher, Johannes A.

PY - 2013/1/17

Y1 - 2013/1/17

N2 - 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.

AB - 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.

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

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