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Reiß, Sebastian ; Schönauer-Kamin, Daniela ; Hagen, Gunter ; Fischerauer, Gerhard ; Moos, Ralf:
Monitoring the ammonia loading of zeolite-based ammonia SCR catalysts by a microwave method.
In: Chemical Engineering & Technology.
Bd. 34
(2011)
Heft 5
.
- S. 791-796.
ISSN 1521-4125
DOI: https://doi.org/10.1002/ceat.201000546
Volltext
Angaben zu Projekten
| Projekttitel: |
Offizieller Projekttitel Projekt-ID Ohne Angabe Mo 1060/6-1 Ohne Angabe Fi956/3-1 |
|---|---|
| Projektfinanzierung: |
Deutsche Forschungsgemeinschaft |
Abstract
Exhaust gas aftertreatment systems, which reduce nitrogen oxide emissions of heavy-duty diesel engines, commonly use a selective catalytic reduction (SCR) catalyst. Currently, emissions are controlled by evaluating NOx or NH3 in the gas phase downstream the catalyst and calculating the NH3 loading via a chemical storage model. Here, a microwave-cavity perturbation method is proposed in which electromagnetic waves are excited by probe feeds and the reflected signals are measured. At distinct resonance frequencies, the reflection coefficient shows a pronounced minimum. These resonance frequencies depend almost linearly on the NH3 loading of a zeolite-based SCR catalyst. Since the NH3 loading-dependent electrical properties of the catalyst material itself are measured, the amount of stored ammonia can be determined directly and in situ. The cross-sensitivity towards water can be reduced almost completely by selecting an appropriate frequency range.