| abstract |
Invention Patent: PROCESS FOR REACTIVATING THERMALLY AGED NITROGEN OXIDE STORAGE CATALYSTS. The present invention relates to nitrogen oxide storage catalysts which are used for the removal of nitrogen oxides contained in the low-mix exhaust gas from so-called low-mix engines. In this case, the purification action is based on the fact that, in a lean mixing operation phase of the engine, nitrogen oxides are stored by the storage catalyst storage material in the form of nitrates, and, in a rich mixing operation of the engine subsequent to this, the nitrates initially formed are decomposed, and the nitrogen oxides, which are released again, are reacted with the exhaust gas fractions that are reduced, in the storage catalyst, to form nitrogen, carbon dioxide and water. Storage catalysts are thermally aged at high temperatures. Aging is based on a sintering of the catalytically active noble metal components of the catalyst and a formation of storage component compounds with the support materials. According to the invention, the composition of the support materials by treatment of the storage material with a mixture of gases containing nitrogen dioxide and / or carbon dioxide, at temperatures between 300 and 50,000, can again be preponderant nullified. The reactivation can be carried out directly on the vehicle, by adjusting the appropriate exhaust gas conditions or occur in the context of routine maintenance, by dismantling the catalyst and treating it with a mixture of gases in a corresponding device. |