EXHAUST EMISSION CONTROL DEVICE FOR DIESEL ENGINE AND EXHAUST EMISSION CONTROL METHOD FOR DIESEL ENGINE

摘要

PROBLEM TO BE SOLVED: To solve such a problem that an Ag catalyst can not reduce NOx discharged from a diesel engine since reaction intermediate remains and the remaining reaction intermediate is re-oxidized by action of an oxidation catalyst 7 although the Ag catalyst 5 which is a selective contact reduction type catalyst durable against SO₂ in exhaust gas of the diesel engine selectively oxidizes nitrogen oxide (NOx) under existence of hydrocarbon compound (HC).;SOLUTION: A reaction intermediate conversion catalyst 6 carrying one or more metals selected out of Cu, V and Fe is arranged in a middle of the Ag catalyst 5 and the oxidation catalyst 7 in a catalytic converter 2 of an exhaust emission control device 1. The reaction intermediate is decomposed by action of the reaction intermediate conversion catalyst 6 and N₂ or the like is formed. Quantity of remaining reaction intermediate is minimized by action of the reaction intermediate conversion catalyst 6 and NOx discharged from the diesel engine can be reduced.;COPYRIGHT: (C)2008,JPO&INPIT