EXHAUST EMISSION CONTROL SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide an exhaust emission control system to enable high efficient removal of nitrogen oxide even when exhaust gas and a catalyst part are at a low temperature area or a high temperature area and besides be excellent in fuel consumption. SOLUTION: A nitrogen oxide purifying part 40 to remove a nitrogen oxide in exhaust gas G1 in exhaust gas passages 2a-2d of an internal combustion engine E is formed such that a first purifying part 41 formed of a selection contact reduction type catalyst to purify a nitrogen oxide by using a reduction agent fed from a reduction agent feed part 61 on the side situated upper stream and a second purifying part 42 formed of a direct reduction type catalyst formed in a state to have a brown millerite type composite oxide are situated in series.