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Mechanistic understanding of Cu-CHA catalyst as sensor for direct NH 3-SCR monitoring : the role of Cu mobility

Titelangaben

Chen, Peirong ; Rizzotto, Valentina ; Khetan, Abhishek ; Xie, Kunpeng ; Moos, Ralf ; Pitsch, Heinz ; Ye, Daiqi ; Simon, Ulrich:
Mechanistic understanding of Cu-CHA catalyst as sensor for direct NH 3-SCR monitoring : the role of Cu mobility.
In: ACS Applied Materials & Interfaces. Bd. 11 (2019) Heft 8 . - S. 8097-8105.
ISSN 1944-8252
DOI: https://doi.org/10.1021/acsami.8b22104

Abstract

The concept to utilize a catalyst directly as a sensor is fundamentally and technically attractive for a number of catalytic applications, in particular, for the catalytic abatement of automotive emission. Here, we explore the potential of microporous copper-exchanged chabazite (Cu-CHA, including Cu-SSZ-13 and Cu-SAPO-34) zeolite catalysts, which are used commercially in the selective catalytic reduction of automotive nitrogen oxide emission by NH3 (NH3-SCR), as impedance sensor elements to monitor directly the NH3-SCR process. The NH3-SCR sensing behavior of commercial Cu-SSZ-13 and Cu-SAPO-34 catalysts at typical reaction temperatures (i.e., 200 and 350 °C) was evaluated according to the change of ionic conductivity and was mechanistically investigated by complex impedance-based in situ modulus spectroscopy. Short-range (local) movement of Cu ions within the zeolite structure was found to determine largely the NH3-SCR sensing behavior of both catalysts. Formation of NH3-solvated, highly mobile CuI species showed a predominant influence on the ionic conductivity of both catalysts and, consequently, hindered NH3-SCR sensing at 200 °C. Density functional theory calculations over a model Cu-SAPO-34 system revealed that CuII reduction to CuI by coadsorbed NH3 and NO weakened significantly the coordination of the Cu site to the CHA framework, enabling high mobility of CuI species that influences substantially the NH3-SCR sensing. The in situ spectroscopic and theoretical investigations not only unveil the mechanisms of Cu-CHA catalyst as sensor elements for direct NH3-SCR monitoring but also allow us to get insights into the speciation of active Cu sites in NH3-SCR under different reaction conditions with varied temperatures and gas compositions.

Weitere Angaben

Publikationsform: Artikel in einer Zeitschrift
Begutachteter Beitrag: Ja
Institutionen der Universität: Fakultäten > Fakultät für Ingenieurwissenschaften
Fakultäten > Fakultät für Ingenieurwissenschaften > Lehrstuhl Funktionsmaterialien > Lehrstuhl Funktionsmaterialien - Univ.-Prof. Dr.-Ing. Ralf Moos
Profilfelder > Advanced Fields > Neue Materialien
Forschungseinrichtungen > Forschungszentren > Bayreuther Materialzentrum - BayMAT
Forschungseinrichtungen > Forschungsstellen > BERC - Bayreuth Engine Research Center
Fakultäten
Fakultäten > Fakultät für Ingenieurwissenschaften > Lehrstuhl Funktionsmaterialien
Profilfelder
Profilfelder > Advanced Fields
Forschungseinrichtungen
Forschungseinrichtungen > Forschungszentren
Forschungseinrichtungen > Forschungsstellen
Titel an der UBT entstanden: Ja
Themengebiete aus DDC: 600 Technik, Medizin, angewandte Wissenschaften > 620 Ingenieurwissenschaften
Eingestellt am: 18 Mär 2019 07:24
Letzte Änderung: 18 Mär 2019 07:24
URI: https://eref.uni-bayreuth.de/id/eprint/47988