| 摘要 |
PROBLEM TO BE SOLVED: To provide an improved performance HC trap catalyst reducing HC emission by making temperature at an inlet side and an outlet side of a catalyst layer rise equally and reducing time difference from start of HC desorption to start of effective purification. SOLUTION: In HC trap catalyst inserted in an exhaust gas passage of an internal combustion engine and carrying a HC absorption layer and the catalyst layer on a carrier, porosity of a carrier inlet side "a" part is reduced by 20% and porosity of an outlet side "b" part is increased by 50% as compared with a comparison example catalyst A having constant porosity (35%) of the carrier formed of ceramics as whole carrier to equalize temperature distribution of the catalyst at the inlet side and the outlet side. Consequently, desorption of HC is delayed and purification is started earlier, and quantity of HC desorbed and discharged without being purified can be reduced. COPYRIGHT: (C)2005,JPO&NCIPI
|
