| abstract |
SOLUTION: The exhaust gas generated by the compressed ignition internal combustion engine (30) for a vehicle and the upstream of the particulate matter filter (44, 50) in the exhaust system are used in the exhaust system. The composite oxidation catalysts (18, 20) have a full length L and a longitudinal axis and extend axially between the first substrate end (I) and the second substrate end (O). Three or more catalyst washcoat zones (1, 2, 3; Or 1, 2, 3, 4), the first catalyst wash coat zone (1) having a length L 1 and L 1 <L is the first base material end portion (I). The second end by the first end (19, 21) of the second catalyst washcoat zone (2), which has a length L 2 and is L 2 <L. Demarcated in the section, the first catalytic washcoat zone (1) contains both platinum and palladium in a weight ratio of the first heat resistant metal oxide supporting material and platinum of ≥1 to palladium. The second catalyst washcoat zone (2) contains the two or more supported platinum group metal components, and the second catalytic wash coat zone (2) contains the second heat-resistant metal oxide supporting material and one or more platinum carried on the upper surface. The third catalytic washcoat zone (3) comprises a third heat resistant metal oxide supporting material and one or more platinum group metal components carried on the upper surface. Cubic of substrate volume, including three or more catalyst washcoat zones defined by the second substrate end (O) at the second end of the third catalyst washcoat zone (3). The total amount of platinum group metal carried in the first catalytic wash coat zone (1), as defined by the number of grams of platinum group metal per foot (g / L) (g / ft 3 ), is the second catalytic wash. A third, larger than the total amount of platinum group metal carried in the coat zone (2), defined by the number of grams (g / L) (g / ft 3 ) of platinum group metal per cubic foot of substrate volume. The total amount of platinum group metal carried in the catalyst wash coat zone (3) is smaller than the total amount of platinum group metal carried in the second catalyst wash coat zone (2), and the first catalyst wash coat zone (1) has a total amount of platinum group metal carried. , Containing one or more first alkaline earth metal components carried on a first heat resistant metal oxide supporting material. [Selection diagram] FIGS. 4 and 5 |