PURPOSE: To clean an exhaust gas of high oxygen concentration containing particulates, HC, and NOx by arranging the first cleaning member of a porous ceramic body carrying a catalyst component at the inlet side of the exhaust gas and a heat resistant porous filter, a porous ceramic layer on which a catalyst component added with a rare earth metal is carried at the outlet side of the exhaust gas.
CONSTITUTION: The first cleaning member, which carries an element selected from alkaline metal elements and Cu, Co, etc., is installed on a porous ceramic substrate which is placed at the inlet side of exhaust gas. A porous ceramic layer carrying a material, which comprises a similar catalyst component as that on the first cleaning member and a rare earth element added, is installed on a heat resistant porous ceramic filter to form the second cleaning member which is placed at the outlet side. The amount of the first catalyst is 0.05-6.0wt.% of the substrate, and the amount of the second catalyst is 6.0wt.% or more of the porous ceramic layer. NOx in the exhaust gas is removed in the presence of HC as a reductant at the inlet side, while particulates, HC, and CO are removed at the outlet side.
MURAMATSU AKIRA
MAKINO SEIJI
YOSHIDA KIYOHIDE
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