| 摘要 |
PROBLEM TO BE SOLVED: To improve hydrocarbon(HC) purifying performance of a catalyst for purifying exhaust gas having an HC adsorbent layer and a three-way catalyst layer. SOLUTION: This catalyst for purifying exhaust gas comprises the HC adsorbent layer 2 formed on the surface of a base material 1, a lower catalyst layer 3 carrying Pd and formed on the surface of the HC adsorbent layer 2, and an upper catalyst layer 4 carrying Pt and Rh and formed on the surface of the lower catalyst layer 3. The HC adsorbent layer 2 adsorbs hydrocarbons at low temperatures, and hydrocarbons discharged from the HC adsorbent layer 2 are oxidized and purified by Pd in the lower catalyst layer 3. Further, CO and NOx are purified by Pt and Rh contained in the upper catalyst layer 4. The heat deterioration of Pd is suppressed, and a trouble, such as a decline in activity, caused by covering Pt an Rh with Pd is prevented. |
