| 摘要 |
<p>This is to provide a catalyst for purifying exhaust gases, catalyst which are good in terms of the purifying performance.
A catalyst according to the present invention for purifying exhaust gases comprises: a catalytic support substrate (1); a first catalytic layer (2) having a first loading layer formed on an upstream side of the catalytic support substrate (1) and made of a fire-resistant inorganic oxide, and Rh loaded in the first loading layer; a second catalytic layer (3) having a second loading layer formed on a surface of the catalytic support substrate (1) on an downstream side of the first catalytic layer (2) and made of a fire-resistant inorganic oxide, and Pd and/or Pt loaded in the second loading layer; and a third catalytic layer (4) having a third loading layer formed on a surface of the second catalytic layer (3) and made of a fire-resistant inorganic oxide, and Rh loaded in the third loading layer; and is characterized in that : the first catalytic layer (2) is such that, when taking Rh loaded in the first catalytic layer as 100% by weight, Rh is loaded in an amount of 70% by weight or more within such a range that the distance from the surface is 20 µm; and the loading amount of Rh loaded in the first catalytic layer (2) is from 1.5 to 15 times as much as the loading amount of Rh loaded in the third loading layer. Because of the fact that Rh is loaded in a great loading amount in the superficial layer portion on an upstream side of exhaust-gas flow, it turns into a catalyst for purifying exhaust gases, catalyst which is good in terms of the purifying characteristics.</p> |
