| Autor: |
J. Theis, M. Eberhardt, E. S. Lox, Ulrich Dr. Göbel, Ralf Riedel |
| Rok vydání: |
2004 |
| Předmět: |
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| Zdroj: |
Topics in Catalysis. :135-142 |
| ISSN: |
1022-5528 |
| DOI: |
10.1023/b:toca.0000029741.48852.e0 |
| Popis: |
Investigations of the aging behavior induced by high temperatures coupled with oxidizing atmosphere of model NOx 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 NOx storage component was present in form of BaCO3. The release of CO2 as a result of the decarbonization of the NOx storage component at increased temperatures was verified by thermogravimetric investigations. In the case of Ba/Al2O3, already during calcination a partial reaction of the NOx 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 NOx storage component has a strong influence on the specific surface area of the model NOx storage systems. The morphology and crystallite size of CeO2 modified with the barium containing NOx storage component exhibited distinct changes compared to the unmodified oxide. The NOx storage efficiency determined by model gas tests of freshly prepared and engine aged model NOx storage catalysts correlates well with the above described observations. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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