| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a catalyst capable of ensuring HC-cleaning performance at a low temperature, having an improved NOx-cleaning efficiency in an oxygen-excess region (lean region), and further to provide a manufacturing method of such a catalyst. <P>SOLUTION: On a first layer containing an adsorbent, there is laminated a second layer containing a catalytic noble-metal and a compound of an alkali metal and an alkaline-earth metal functioning as a NOx-adsorbent. In this case, a powder carrier such as alumina, etc. is impregnated with a solution of at least one element selected from alkali metals and alkaline-earth metals, and the element is fixed as an oxide. The powder carrier, on which the catalytic noble metal is carried and the above element fixed as an oxide is fixed further as an carbonate, is applied in the form of slurry on the first layer. In this case, the particle size of the carbonate of the element is made up to at most 200 nm, and the content of the element in the first layer is made up to at most 1% in terms of the metal. <P>COPYRIGHT: (C)2004,JPO |
