| 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 purification 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 consists of a first catalyst layer containing a component of one or more kinds selected from 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 alumina and/or silica, and a third catalyst layer containing a zoelite continuing copper Cu and/or cobalt Co component, and β-zeolite and/or Y-zeolite. 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 internal composition engine whose exhaust gas contains >=14.7 airfuel ratio, >=5% oxygen concn. and <=10 HC/NOx ratio. |
