NO x -storage catalysts (NSC) with varied washcoat compositions have been investigated experimentally under lean and rich conditions. Besides the fact that Ba and Rh are essential for NO x -storage and -reduction, it was observed that Ba accelerates the NO-reduction and decreases NO-oxidation kinetics. It also turned out to be the promoting species regarding water gas shift reaction. The results revealed kinetic inhibition effects by CO, C 3 H 6 and NO, being less pronounced with Ba in the washcoat. It is further shown that the cyclic NO x -conversion of the NSC is mainly determined by the processes in the regeneration phase.

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