| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an antifreeze urea solution free from freezing even in an arctic region to attain high NO<SB>x</SB>purification performance with a simple system structure. <P>SOLUTION: The antifreeze urea solution supplied to a feed valve 3 from an urea solution tank 4 is jetted to a SCR catalyst 22 mounted on an exhaust path 11 of an internal combustion engine. The antifreeze urea solution is a mixed solution of an urea aqueous solution of high concentration of ≥30 wt.% with a 1-7C alcoholic organic solvent having hydrophilic group, wherein the mixing ratio of the alcoholic organic solvent to the urea aqueous solution is (urea solution):(alcoholic organic solvent)≥7:1 ( volume ratio) and the freezing point is ≤-30°C. <P>COPYRIGHT: (C)2009,JPO&INPIT |
