| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust gas purifying system wherein a predetermined or higher NOx purifying rate is shown by efficiently purifying CO and HC in a wide purifying temperature range or particularly in a low temperature range of about 300°C and, by efficiently purifying the NOx of an oxygen excess range to be exhausted from an internal combustion engine. <P>SOLUTION: The exhaust gas purifying system comprises an NOx adsorbent and an NOx purifying catalyst sequentially arranged in this order from the upstream side of an exhaust passage, so that the air fuel ratio of the internal combustion engine can be arbitrarily switched. In this system, the adsorbent adsorbs NOx when the exhaust gas is in a lean region and discharges the NOx when the exhaust gas is in a rich region and/or a stoichiometric region, and the NOx purifying catalyst reduces and purifies the NOx when the catalyst is in the rich region and/or the stoichiometric region. When a cerium component of 10 to 120 g/L is contained. The means crystal grain size of the cerium compound is 40 nm or less. <P>COPYRIGHT: (C)2004,JPO |
