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Fundamental Investigations of Thermal Aging Phenomena of Model NOxStorage Systems

Eberhardt, M. and Riedel, R. and Göbel, U. and Theis, J. and Lox, E. S. (2004):
Fundamental Investigations of Thermal Aging Phenomena of Model NOxStorage Systems.
30/31, In: Topics in Catalysis, Springer, Netherlands, pp. 135-142, ISSN 1022-5528, DOI: 10.1023/B:TOCA.0000029741.48852.e0,
[Online-Edition: https://doi.org/10.1023/B:TOCA.0000029741.48852.e0],
[Article]

Abstract

Investigations of the aging behavior induced by high temperatures coupled with oxidizing atmosphere of model NO x storage systems Ba/Al2O3 and Ba/CeO2 are reported in this paper. The samples were prepared, calcined and exposed to temperatures between 500 and 1000 °C in air for 12 h for thermal aging. Samples were characterized with XRD, HRSEM, DSC-TGA-MS and BET analyses. In XRD investigations of all model systems calcined at 500 °C for 2 h, the NO x storage component was present in form of BaCO3. The release of CO2 as a result of the decarbonization of the NO x storage component at increased temperatures was verified by thermogravimetric investigations. In the case of Ba/Al2O3, already during calcination a partial reaction of the NO x storage component with Al2O3 resulting in the formation of barium aluminate was observed. In the model system Ba/CeO2 the decomposition of the barium carbonate started above 780 °C and the formation of a barium cerium mixed oxide was observed. The presence of the barium containing NO x storage component has a strong influence on the specific surface area of the model NO x storage systems. The morphology and crystallite size of CeO2 modified with the barium containing NO x storage component exhibited distinct changes compared to the unmodified oxide. The NO x storage efficiency determined by model gas tests of freshly prepared and engine aged model NO x storage catalysts correlates well with the above described observations.

Item Type: Article
Erschienen: 2004
Creators: Eberhardt, M. and Riedel, R. and Göbel, U. and Theis, J. and Lox, E. S.
Title: Fundamental Investigations of Thermal Aging Phenomena of Model NOxStorage Systems
Language: English
Abstract:

Investigations of the aging behavior induced by high temperatures coupled with oxidizing atmosphere of model NO x storage systems Ba/Al2O3 and Ba/CeO2 are reported in this paper. The samples were prepared, calcined and exposed to temperatures between 500 and 1000 °C in air for 12 h for thermal aging. Samples were characterized with XRD, HRSEM, DSC-TGA-MS and BET analyses. In XRD investigations of all model systems calcined at 500 °C for 2 h, the NO x storage component was present in form of BaCO3. The release of CO2 as a result of the decarbonization of the NO x storage component at increased temperatures was verified by thermogravimetric investigations. In the case of Ba/Al2O3, already during calcination a partial reaction of the NO x storage component with Al2O3 resulting in the formation of barium aluminate was observed. In the model system Ba/CeO2 the decomposition of the barium carbonate started above 780 °C and the formation of a barium cerium mixed oxide was observed. The presence of the barium containing NO x storage component has a strong influence on the specific surface area of the model NO x storage systems. The morphology and crystallite size of CeO2 modified with the barium containing NO x storage component exhibited distinct changes compared to the unmodified oxide. The NO x storage efficiency determined by model gas tests of freshly prepared and engine aged model NO x storage catalysts correlates well with the above described observations.

Journal or Publication Title: Topics in Catalysis
Volume: 30/31
Publisher: Springer, Netherlands
Uncontrolled Keywords: NOx storage catalyst, lean-burn, thermal aging, barium, ceria
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Dispersive Solids
Date Deposited: 17 Dec 2018 11:55
DOI: 10.1023/B:TOCA.0000029741.48852.e0
Official URL: https://doi.org/10.1023/B:TOCA.0000029741.48852.e0
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