A Gas Sensing Approach to Gain Insight into the Mechanism of DeNOx-SCR over Fe-ZSM-5 Catalysts

Titelangaben

Rizzotto, Valentina ; Chen, Peirong ; Hagen, Gunter ; Moos, Ralf ; Simon, Ulrich:
A Gas Sensing Approach to Gain Insight into the Mechanism of DeNOx-SCR over Fe-ZSM-5 Catalysts.
In: 17th International Meeting on Chemical Sensors - IMCS 2018. - Wien , 2018 . - S. 134-135
ISBN 978-3-9816876-9-9
DOI: https://doi.org/10.5162/IMCS2018/GS3.5

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Abstract

In order to meet the legislative emission requirements for NOx emission, selective catalytic reduction (DeNOx-SCR) catalysts, in particular zeolites, are used. To improve their catalytic performance, an in-depth understanding of the reaction mechanisms is required based on an analysis of the physicochemical properties, preferably in situ. We introduce a setup combining impedance spectroscopy (IS) and infrared spectroscopy in diffuse reflection mode (DRIFT) for in situ measurements on zeolites under SCR-related conditions. By means of this gas sensing approach, we observed the formation of ammonium ion (NH4+) intermediates resulting from the interaction of NO and NH3 on Fe-ZSM-5 catalysts. The formed NH4+ intermediates, indicating the activation of NO in the presence of adsorbed NH3, were found to correlate to the NH3−SCR activity of Fe-ZSM-5 catalysts at low temperatures. These findings, which are not easily achievable by conventional methods, provide new and important perspectives to understand mechanistically the NH3−SCR reaction over Fe-zeolite catalysts.