EXHAUST EMISSION CONTROL METHOD AND EXHAUST EMISSION CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide a method and a device for efficiently purifying nitrogen oxides of an internal combustion engine start period. SOLUTION: An NO oxidizing device and a nitrogen oxides trapping catalyst are installed in an exhaust gas passage of an internal combustion engine to purify the nitrogen oxides in exhaust gas of the internal combustion engine start period. To be specific, the NO oxidizing device 3 and the nitrogen oxides trapping catalyst 4 are installed in order in an exhaust pipe 2 from the engine 1. NO exhausted from the engine 1 flows into the NO oxidizing device 3. The NO inside the exhaust gas is oxidized into NO2 by the NO oxidizing device 3. Then the exhaust gas containing the NO2 flows into the nitrogen oxides trapping catalyst 4 and the NO2 is trapped by the nitrogen oxides trapping catalyst.