| 摘要 |
<p>When the temperature of NOx reducing catalyst disposed in an engine exhaust pipe becomes higher than given value, a liquid capable of lowering the exhaust temperature by evaporation heat is appropriately injected on an exhaust upstream position with respect to the NOx reducing catalyst. The above given value refers to a temperature having no adverse impact on the NOx reducing catalyst, in particular, a temperature slightly lower than the heat resistance limit of the support or components of the catalyst. As the liquid, use is made of an increment of liquid reducing agent or precursor thereof fed to the NOx reducing catalyst, or water.</p> |
