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Molecular understanding of catalyst as sensor : an in situ impedance-DRIFT spectroscopy study of NH3-SCR reaction on zeolites

Title data

Chen, Peirong ; Schönebaum, Simon ; Rauch, Dieter ; Moos, Ralf ; Simon, Ulrich:
Molecular understanding of catalyst as sensor : an in situ impedance-DRIFT spectroscopy study of NH3-SCR reaction on zeolites.
2016
Event: EMRS Spring Meeting 2016 , 2.5.-6.5.2016 , Lille, France.
(Conference item: Conference , Speech )

Abstract in another language

Selective catalytic reduction of nitrogen oxides (NOx) by NH3 (NH3-SCR) is one of the most promising strategies for the abatement of NOx emissions from diesel engines. To further improve the efficiency of NH3-SCR, it is necessary to get insights into the real-time state of the applied catalysts (mostly zeolite-based) under operational conditions. As revealed in our previous studies by impedance spectroscopy (IS), the proton transport in H-ZSM-5 was supported by stored NH3 as a solvate molecule, which allows H-ZSM-5 zeolites to be used in the sensing of both gas-phase NH3 and NH3-SCR reactions. Here, we performed in situ IS studies on highly comparable zeolites Fe-ZSM-5 and Cu-ZSM-5 (with the Cu or Fe species predominantly in isolated state) as catalysts and sensors simultaneously under SCR-related conditions. While the SCR conversion of stored NH3 on Fe-ZSM-5 can be effectively monitored based on NH3-supported proton transport, the sensing of SCR conversion of stored NH3 on Cu-ZSM-5 was significantly influenced by the formation of intermediates. Simultaneous IS and DRIFTS (diffuse reflection infrared Fourier transform spectroscopy) studies revealed that ammonium ions formed immediately by exposing NH3-saturated Cu-ZSM-5 to NO-containing atmospheres, and subsequently dominated the proton conductivity. Such a correlation of integral electrical response with molecular processes, achieved by our IS-DRIFTS studies, not only clarifies the molecular origin of the NH3-SCR sensing effect, but also provides a new perspective to understand the NH3-SCR mechanism over metal-promoted zeolites.

Further data

Item Type: Conference item (Speech)
Refereed: Yes
Institutions of the University: Faculties > Faculty of Engineering Science
Faculties > Faculty of Engineering Science > Chair Functional Materials > Chair Functional Materials - Univ.-Prof. Dr.-Ing. Ralf Moos
Profile Fields > Advanced Fields > Advanced Materials
Research Institutions > Research Centres > Bayreuth Center for Material Science and Engineering - BayMAT
Faculties
Faculties > Faculty of Engineering Science > Chair Functional Materials
Profile Fields
Profile Fields > Advanced Fields
Research Institutions
Research Institutions > Research Centres
Result of work at the UBT: Yes
DDC Subjects: 600 Technology, medicine, applied sciences > 620 Engineering
Date Deposited: 17 May 2016 08:23
Last Modified: 17 May 2016 08:23
URI: https://eref.uni-bayreuth.de/id/eprint/32386