| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control system having improved NOx purifying performance even in a low temperature region of 250°C or lower. <P>SOLUTION: The exhaust emission control system which has a CO<SB>2</SB>absorbing material, a H<SB>2</SB>generating catalyst and a NOx catalyst arranged in an exhaust gas flow path in an internal combustion engine comprises a means for measuring these temperatures, a reduction component increasing means, and a means for increasing the temperature of exhaust gas. The H<SB>2</SB>generating catalyst generates hydrogen from water vapor and carbon monoxide with gas shift reaction, and the NOx catalyst adsorbs NOx in the exhaust gas when lean and gives reduction purification thereto when rich. Herein, the exhaust gas increased by the means for increasing the temperature of the exhaust gas has a temperature or higher at which the CO<SB>2</SB>absorbing material releases CO<SB>2</SB>and lower than a temperature 50°C higher than that temperature. In the system, the NOx catalyst contains a Pt or Rh and Ce oxide and an oxide including alkaline metals and generating free energy G of the reaction of the oxide of the alkaline metals with CO<SB>2</SB>at 300°C is smaller than the ΔG of the oxide of the alkaline metals contained in the H<SB>2</SB>generating catalyst. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
