Eberhardt, M. ; Riedel, R. ; Göbel, U. ; Theis, J. ; Lox, E. S. (2004)
Fundamental Investigations of Thermal Aging Phenomena of Model NOxStorage Systems.
In: Topics in Catalysis, 30/31
doi: 10.1023/B:TOCA.0000029741.48852.e0
Artikel, Bibliographie

Kurzbeschreibung (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.

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