| 摘要 |
PROBLEM TO BE SOLVED: To provide a catalyst for purification of exhaust gas and a purifying method of exhaust gas by which NOx unification performance can be improved even in a low temp. region at a low HC/NOx ratio where a conventional catalyst can not show enough purification performance, and the deterioration of the catalyst can be suppressed even under high temp. hydrothermal conductions. SOLUTION: This catalyst for purification of exhaust gas exhaust gas consists of a first catalyst layer containing component of one or more kinds selected from among platinum Pt, palladium Pd and rhodium Rh and a component of one or more kinds selected from among alkali metals, alkaline earth metals and rare earth metals, a second catalyst layer containing β-zeolit containing a cobalt component Co, and a third catalyst layer continuing a zeolite containing copper Cu and/or cobalt Co component. The second catalyst layer is formed on the first catalyst layer, and the third catalyst layer is formed on the second layer. Preferably, the catalyst for purification of exhaust gas is used for an inner combustion engine whose exhaust gas has >=14.7 air-fuel ratio, >=5% oxygen concn. and <=10 HC/NOx ratio. |
