| 摘要 |
PURPOSE:To enhance CO-purifying capacity as a low temp., by a method wherein upper and lower two activated alumina layers are laminated to the surface of a base material and platinum or Pd is supported by the lower layer while Ph and platinum or Rh and Pd are supported by the upper layer. CONSTITUTION:Upper and lower two activated alumina layers are laminated to the surface of a base material comprising cordierite and platinum or Pd is supported by the lower layer while Rh and platinum or Rh and Pd are supported by the upper layer. With respect to the amount of each catalytic metal, Rh is 0.1- 0.3g/l or Pt or Pd is about 0.5g/l in the upper layer while Pt or Pd is about 0.5g/l in the lower layer. Because this catalyst supports not only Rh having strong poisoning resistance to CO, lead or phosphorus only in the upper layer thereof but also platinum or Pd in a proper amount, platinum or Pd in the lower layer is protected. In addition, because CO-oxidation in the lower layer is facilitated by diffusing CO in the upper layer, the ignition temp. of CO is lowered and this catalyst shows excellent purifying capacity even at a lower temp. as compared with a conventional one. |
