SCR and NO oxidation over Fe-ZSM-5 - The influence of the Fe content

Beitrag in einer Fachzeitschrift
(Originalarbeit)


Details zur Publikation

Autor(en): Ellmers I, Velez RP, Bentrup U, Schwieger W, Brückner A, Gruenert W
Zeitschrift: Catalysis Today
Verlag: Elsevier
Jahr der Veröffentlichung: 2015
Band: 258
Seitenbereich: 337-346
ISSN: 0920-5861


Abstract


Fe-ZSM-5 catalysts (Si/Alin ZSM-5-14) were prepared by different routes and used for an investigation of relations between normalized reaction rates (rates per Fe atom present) and Fe content in reactions relevant for NO abatement by selective catalytic reduction (SCR) with NH3: standard SCR, fast SCR, and NO oxidation. Samples were characterized by XRD, ex situ UV-vis and EPR spectroscopy. In standard SCR, normalized reaction rates increased with Fe content to a maximum around 0.5 wt.% (Fe/Al approximate to 0.07) and decreased at further growing Fe loading. This suggests the existence of Fe sites of different activity, which we identify with isolated Fe3+ sites (on alpha and/or beta cation positions, lower activity) and Fe3+ in small oligomeric structures (higher activity) on the basis of our characterization data and recent results from operando-EPR experiments (Perez Velez et al., 2014). The decay with further increasing Fe loading is assigned to Fe being included in more aggregated structures. Normalized reaction rates of NO oxidation to NO2 decrease from very small Fe contents on, which indicates that NO oxidation is catalyzed by a small minority of Fe sites, most likely by a variety of isolated sites, in strong contrast to standard SCR. Normalized reaction rates for fast SCR are difficult to establish due to complexity and high rate of the reaction. The results suggest, however, that fast SCR proceeds on a small minority of Fe sites as well, in agreement with our recent operando EPR and Moessbauer studies (Perez Velez et al., 2014). Fast SCR proceeds also in absence of Fe, but rates are inferior and easily exceeded even by contributions arising from Fe impurities usually present in technical zeolites. (C) 2015 Elsevier B.V. All rights reserved.



FAU-Autoren / FAU-Herausgeber

Schwieger, Wilhelm Prof. Dr.
Professur für Technische Chemie (Reaktionstechnik)


Autor(en) der externen Einrichtung(en)
Leibniz-Institut für Katalyse (LIKAT) / Leibniz Institute for Catalysis
Ruhr-Universität Bochum (RUB)


Zitierweisen

APA:
Ellmers, I., Velez, R.P., Bentrup, U., Schwieger, W., Brückner, A., & Gruenert, W. (2015). SCR and NO oxidation over Fe-ZSM-5 - The influence of the Fe content. Catalysis Today, 258, 337-346. https://dx.doi.org/10.1016/j.cattod.2014.12.017

MLA:
Ellmers, Inga, et al. "SCR and NO oxidation over Fe-ZSM-5 - The influence of the Fe content." Catalysis Today 258 (2015): 337-346.

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Zuletzt aktualisiert 2018-07-08 um 05:38