EXHAUST GAS DECONTAMINATION SYSTEM AND METHOD OF EXHAUST GAS DECONTAMINATION

An exhaust gas decontamination system and a method of exhaust gas decontamination wherein in the regeneration of NOx occlusion reduction type catalyst with respect to a lean-burn engine or diesel engine, even in the instance of rich burning accompanied by EGR, the NOx released from the NOx occlusion reduction type catalyst can satisfactorily be reduced and purged to thereby exhibit a high NOx removal ratio. The exhaust gas decontamination system (1) provided with the NOx occlusion reduction type catalyst (30) includes control unit (C1) comprising normal control operation means (C10), regeneration control initiation judging means (C20), catalyst activation control operation means (C30) and rich-burn control operation means (C40) capable of lowering the concentration of oxygen in the exhaust gas so as to realize such a constitution that the catalyst is carried out just before rich burning accompanied by EGR.