A process for the regeneration of nitrogen oxides storage catalysts

Nitrogen oxide storage catalysts for purifying the exhaust gas from lean-burn engines are periodically regenerated by switching the engine from lean operation to rich operation. After regeneration, the motor is switched back to lean operation. In the exhaust line from the engine to the catalyst is at this time still rich exhaust gas, which is ejected by the subsequent lean exhaust gas over the catalyst in the environment. This leads to short-term peak emissions of the rich exhaust gas components and degrades the achievable exhaust emission. To solve the problem it is proposed to create oxidizing conditions by blowing air before the storage catalyst so that the still in the exhaust pipe upstream of the storage catalyst rich exhaust gas components can be implemented on the storage catalyst to innocuous products. Especially in already damaged by aging in their storage catalysts, which have to be much more common than fresh catalysts regenerated, the proposed method can lead to a significant improvement in emission control.