| abstract |
A catalyst for purifying exhaust gases includes a heat resistant support, a porous layer coated on the heat resistant support, a noble metal catalyst ingredient loaded on the porous layer, and an NO X storage component including at least one member selected from the group consisting of alkaline-earth metals, rare-earth elements and alkali metals, and loaded on the porous layer. In the catalyst, the noble metal catalyst ingredient and the NO X storage component are disposed adjacent to each other, and are dispersed uniformly in the porous layer. In fuel-lean (i.e., oxygen-rich) atmospheres, NO present in exhaust gases is oxidized to N0 2 by the noble metal catalyst ingredient, and at the same time the resulting N0 2 is stored in the NO X storage component which is disposed adjacent to the nobel metal catalyst. In the stoichiometric or fuel-rich (i.e., oxygen-lean) atmospheres, the stored N0 2 is released, and simultaneously urged to react with HC and CO present in exhaust gases by the action of the noble metal catalyst ingredient which is disposed adjacent to the NO x storagecomponent. Hence, the catalyst is improved in terms of NO x purifying performance. |