The use of ethanol as a reducing agent on a silver-base catalyst in the presence of oxygen has a strong reductive effect on NOx emitted from a diesel engine. However, it is possible that nitrous oxide (N_2O) will be formed without reduction of NOx to nitrogen. In this study, an experimental NOx reduction apparatus was constructed, and model experiments on NOx reduction with atmosphere and catalyst temperature simulating those in actual exhaust gas were carried out. Furthermore, the correlations of NOx reduction rate with amount of N_2O produced as well as with ethanol decomposition and oxidized components were investigated. The results showed that N_2O is produced during the process in which acetaldehyde is formed from ethanol.
