PURPOSE: To clean effectively an exhaust gas of high oxygen concentration containing particulates, HC, and NOx by arranging cleaning members comprising a porous ceramic layer carrying a catalyst component, a porous ceramic body, a heat resistant porous filter carrying a platinum group element in sequence from the inlet side to the outlet side of the exhaust gas.
CONSTITUTION: A porous ceramic layer is installed on a heat resistant porous filter as the first cleaning member on which a catalyst consisting of alkali metals, Cu, etc., rare earth elements is supported. The second cleaning member consists mainly of a porous ceramic body. As the third cleaning member, a heat resitant porous filter carries a platinum group element. These three members are arranged in sequence from the inlet side to the outlet side of exhaust gas. When an exhaust gas of high oxygen concentration containing particulates, HC, and NOx is passed through these cleaning members, particulates are burned at lower temperatures in the first cleaning member, HC is reduced in the second cleaning member, and then the residual HC and CO are oxidized in the third cleaning member, so that the exhaust gas is effectively cleaned.
KADOYA SATOSHI
YOSHIDA KIYOHIDE
FURUYAMA MASATAKA
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