| 摘要 |
PROBLEM TO BE SOLVED: To efficiently reduce and decompose NOx by providing a first catalyst for adsorbing aromatic hydrocarbon in exhaust emission, and a second catalyst for reducing NOx in exhaust gas by reacting the aromatic hydrocarbon adsorbed by the first catalyst with the NOx. SOLUTION: An exhaust emission purifying catalyst provided in the exhaust passage of a diesel engine comprises a first catalyst (HC adsorbent) 5 having Zr suitable for adsorption of aromatic hydrocarbon, which is supported by zeolite 4 as a base material (support material), and a second catalyst 6 having Pt suitable for reductive purification of NOx in oxygen excess atmosphere, which is similarly supported by the zeolite 4. In the first catalyst 5, a metal element for adsorbing the aromatic hydrocarbon is preferably bonded to the acid point of the zeolite. The metal element suitable for adsorption of the aromatic hydrocarbon is chemically bonded to the acid point, whereby the acid point intensity of this part is enhanced.
|
