The precious metal which supports in catalytic converter support formation and the said catalytic converter

摘要

PROBLEM TO BE SOLVED: To provide an exhaust gas cleaning catalyst in which a catalytic metal can be activated in a period of time as short as possible from a low-temperature zone and to provide a method of evaluating the cleaning activity of this catalyst accurately in the low-temperature zone.;SOLUTION: A catalyst depositing layer is composed of an oxide satisfying the expression: C₁²/λ₁≤0.04, wherein C₁ is heat capacity; λ₁ is thermal conductivity. The heat energy of exhaust gas is efficiently absorbed in the catalyst depositing layer and a noble metal is warmed up rapidly to the activated temperature by the exhaust gas. Therefore, the time until the catalyst exhibits satisfactory activity is shortened even when an engine is started and subsequently the cleaning ability of the catalyst is improved.;COPYRIGHT: (C)2004,JPO