Engine exhaust gas purification catalyst and exhaust gas purifier
AssigneeNissan Motor Co., Ltd.
InventorsShinji Yamamoto, Satomi Etou, Masahiro Takaya
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Abstract
In a catalyst unit which purifies the exhaust gas of an engine, a first layer comprising a zeolite hydrocarbon adsorbent is formed on a monolithic substrate. A catalyst layer comprising palladium, platinum or rhodium as a three way catalyst is formed on the first layer. The Geometrical Surface Area of the monolithic substrate is set in the range of 10-35 cm.sup.2 /cm.sup.3. The weight ratio of the first layer and the catalyst layer is set to from 9:1 to 1:4.
Claims31
A catalyst unit for purifying the exhaust gas of an engine, comprising:
- a monolithic substrate having a Geometrical Surface Area in the range 10-35 cm.sup.2 /cm.sup.3,
- a first layer comprising a zeolite hydrocarbon adsorbent formed on said monolithic substrate, and
- a catalyst layer comprising any one or palladium, platinum and rhodium as a three-way catalyst, said catalyst layer being formed on said first layer, and the weight ratio of said first layer to said catalyst layer lying in the range of 9:1 to 1:4.
An exhaust purification device for purifying the exhaust gas of an engine, comprising:
- a first catalyst unit comprising a monolithic substrate having a Geometrical Surface Area in the range 10-35 cm.sup.2 /cm.sup.3, a first layer comprising a zeolite hydrocarbon adsorbent formed on said monolithic substrate, and a catalyst layer comprising any one of palladium, platinum and rhodium as a first three-way catalyst, said catalyst layer being formed on said first layer, and the weight ratio of said first layer to said catalyst layer lying in the range of 9:1 to 1:4, and
- a second catalyst unit installed upstream of said first catalyst unit, second catalyst unit supporting any one of palladium, platinum and rhodium as a second three-way catalyst, wherein a support concentration of said second three-way catalyst is set in the range of 4-20 weight %, and the support amount of said second three-way catalyst is set in the range of 100-1000 g/ft.sup.3,
- wherein the amount of hydrocarbon absorbed by said first layer is set equal to or less than 70% of the hydrocarbon saturation adsorption amount of said hydrocarbon adsorbent.
An exhaust purification device for purifying the exhaust gas of an engine, comprising:
- a first catalyst unit comprising a monolithic substrate having a Geometric Surface Area in the range 10-35 cm.sup.2 /cm.sup.3, a first layer comprising a zeolite hydrocarbon adsorbent formed on said monolithic substrate, and a catalyst layer comprising rhodium as a first three-way, catalyst, said catalyst layer being formed on said first layer, and the weight ratio of said first layer to said catalyst layer lying in the range of 9:1 to 1:4, and
- a second catalyst unit installed upstream of said first catalyst unit, said second catalyst unit supporting rhodium as a second three-way catalyst, wherein a support concentration of said second three-way catalyst is set in the range of 4-20 weight %, the support amount of said second three-way catalyst is set in the range of 100-1000 g/ft.sup.3,
- wherein the amount of hydrocarbon absorbed by said first layer is set equal to or less than 70% of the hydrocarbon saturation adsorption amount of said hydrocarbon adsorbent, and an amount of rhodium as the second three-way catalyst is set less than the amount of rhodium as the first three-way catalyst.
Dependencies are inferred from the claim text.