Abstract: When a nitrogen oxide storage catalyst is being regenerated, the regeneration may be terminated for example as a result of a premature load change in the engine, which can lead to incomplete emptying of the storage catalyst. The residual filling level which remains in the catalyst following an incomplete regeneration of this nature is used as the starting value for calculation of the filling level during the next storage phase. After incomplete regeneration, the nitrogen oxide conversion rate is initially greater than would be expected, on account of the residual filling level. By taking this increased conversion rate into account when calculating the filling level during the storage phase, it is possible to further improve the accuracy of the calculation.

Abstract: The invention relates to a catalyst for lowering the amount of NOx in the lean exhaust gas from lean burn engines, comprising active aluminum oxide, magnesium oxide and at least one noble metal of the platinum group of the periodic table of the elements, as well as at least one nitrogen oxide storage material. The catalyst is characterized in that the magnesium oxide forms a homogeneous mixed oxide with aluminum oxide and is present in a concentration of about 1 to about 40 wt.-%, based on the total weight of the mixed oxide.

Abstract: The invention relates to a catalyst for lowering the amount of NOx in the lean exhaust gas from lean burn engines, comprising active aluminum oxide, magnesium oxide and at least one noble metal of the platinum group of the periodic table of the elements, as well as at least one nitrogen oxide storage material. The catalyst is characterized in that the magnesium oxide forms a homogeneous mixed oxide with aluminum oxide and is present in a concentration of about 1 to about 40 wt.-%, based on the total weight of the mixed oxide.