| 摘要 |
PROBLEM TO BE SOLVED: To efficiently carry out exhaust emission controlling over a wide temperature range from low temperature to high temperature by preparing a reducing agent introduced in exhaust gas before treatment from an alcohol solution of urea when NOx in the exhaust gas is subjected to the selection reducing treatment by a catalyst. SOLUTION: A reducing agent introduced in exhaust gas before a treatment when NOx in the exhaust emission of internal combustion engine is selectively reduced by a catalyst is prepared from an alcohol solution of urea. The exhaust gas to which the reducing agent from an injection nozzle 5 is introduced is successively brought into contact with a NOx reducing catalyst of urea, NOx reducing catalyst 7 of alcohol, and an oxidation catalyst 8 of ammonia and alcohol, thereby reducing NOx in the exhaust gas. Alcohol (1-7C alcohol, for example) used for preparing the reducing agent having low specific gravity and low freezing point (fusing point), such as methyl alcohol, ethyl alcohol, and isopropyl alcohol, for example, is used. |
