EXHAUST EMISSION CONTROL CATALYST DEVICE AND EXHAUST EMISSION CONTROL METHOD

摘要

PROBLEM TO BE SOLVED: To allow for efficient NOremoval within a wide temperature range of exhaust gas.SOLUTION: A NOtrap part 3 including NOadsorption/storing material capable of adsorbing NOwhen an exhaust gas temperature is 100°C or more and 200°C or less and capable of storing NOwhen an exhaust gas temperature is 350°C or more and 450°C or less is disposed in an exhaust gas passage 2 of an engine, and a NOstoring and reducing catalyst 4 capable of absorbing NOwhen an air-fuel ratio of the exhaust gas is lean and capable of reducing NOwhen the air-fuel ratio of the exhaust gas is rich is disposed downstream from the NOtrap part in an exhaust gas flow direction.