| abstract |
This invention relates to a catalyst for exhaust gas purification, including a substrate, a coat layer comprised of a porous support body formed on the substrate, and a noble metal supported on the coat layer. In the coat layer, pore volume of pore having pore diameter 0.1 to 20 mu m occupies 50 % or more, and pore volume of pore having pore diameter 0.5 to 10 mu m occupies 20 % or more, respectively of a pore volume of pore having pore diameter 50 mu m or less. The pore diameter of the coat layer is 10 to 2000 times that of the conventional coat layer. Gas diffuse speed in the pore of the present invention is 10 to 2000 times that of the conventional pore. On account of the noble metal supported at the inner part of the coat layer, particle growth of the noble metal is prevented, and utilize efficiency of the NOx storing material at the inner part is increased. Both increasing of NOx storing amount in the lean condition under oxygen excessive atmosphere, and reducing and purifying of NOx of high efficiency by the short time rich-spike can be realized. |