| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control system for compatibly attaining NOx reduction elimination characteristics and HC oxidation elimination characteristics by actualizing a compact catalyst. <P>SOLUTION: The exhaust emission control system comprises: an NOx trapping material for absorbing nitrogen oxide when an excess air ratio λ of exhaust gas exceeds 1 and for desorbing the nitrogen oxide when the λ is 1 or smaller; a conversion catalyst; and an O2 control means for controlling oxygen concentration in the exhaust gas. When the λ of the exhaust gas exceeds 1, the NOx trapping material absorbs NOx, and when the λ is 1 or smaller, the O2 control means controls the oxygen concentration in the exhaust gas at the inlet of the conversion catalyst to be 0.8-1.5 vol% and reduces the NOx desorbed from the NOx trapping material. <P>COPYRIGHT: (C)2009,JPO&INPIT |
