| 摘要 |
PROBLEM TO BE SOLVED: To provide a cleaning method for exhaust gas in which NOX is efficiently cleaned by bringing exhaust gas adding hydrocarbon into contact with a noble metallic catalyst. SOLUTION: Particle diameter of noble metal particles carried in the part on the side of a porous carrier, into which exhaust gas is introduced, is made larger than particle diameter of the noble metal particles carried in the part on the side of the porous carrier from which exhaust gas is led out. The noble metal particles having large average particle diameter on the introduction side are reduced by hydrocarbon. In this case, the introduced paraffin-based hydrocarbon is decomposed and olefin-based hydrocarbon is produced. The noble metal particles with small average particle diameter on the leading out side are easily reduced by olefin-based hydrocarbon and activated and NOX is efficiently cleaned. |
