Apparatus for reducing nitrogen oxide contained in exhaust gas

An apparatus for reducing nitrogen oxide contained in exhaust gas, comprising:

• a diesel oxidation catalyst (DOC) device primarily oxidizing an exhaust materials containing total hydrocarbon (THC) and carbon monoxide (CO) in the exhaust gas by using a first diesel oxidation catalyst (DOC);
• a catalyzed particulate filter (CPF) device mounted downstream of the DOC device so as to receive the exhaust gas that is primarily oxidized by the DOC device, further oxidizing the exhaust materials containing the THC and the CO by heat generated during the primary oxidation and an oxidizing agent coated therein, and oxidizing nitrogen monoxide (NO) in the exhaust gas into nitrogen dioxide (NO2) by using the generated heat and the oxidizing agent coated therein;
• a nozzle mounted downstream of the CPF device, and dosing a reductant to the exhaust gas;
• and
• a selective catalytic reduction (SCR) device mounted downstream of the nozzle, and reducing nitrogen oxide (NOx) in the exhaust gas into nitrogen gas (N2) by using the NO2 generated in the CPF device and the reductant.