| 摘要 |
PURPOSE:To enhance the efficiency in removing NOX by forming a first wash coat layer of Cu/zeolite structure on a carrier on its front side and the first and second wash coat layers on the carrier on its rear side. CONSTITUTION:The NOX exhausted from a lean burn engine in the steady running are decomposed at the active site of the Cu/zeolite structure of the first wash coat layer 22, and the HC, CO and NOX exhausted from the engine are simultaneously reduced in the transient running carried out with the theoretical air-to-fuel ratio at the active site of the noble-metal elements such as Pt, Rh and Pd deposited on the second wash coat layer 23. Since the Cu/ zeolite structure is formed in this way on the front side of a carrier 15, the reducing agents such (H2, HC, etc.,) are secured close to the active site of the Cu/zeolite structure, and the efficiency in removing NOX is improved. |
