Exhaust gas purifying catalyst comprising a catalyst layer comprising at least two inorganic porous particles
An exhaust gas purifying catalyst comprising a catalyst layer comprising two or more types of inorganic porous particles each having a different particle size, a catalytically active component, and voids, wherein; as a first characteristic, 50% or more by number of all the voids in the catalyst layer satisfies a condition of the following (formula 1); L/2/(πS) 1/2 ≧2 . . . (formula 1) wherein S represents a void cross-sectional area, and L represents a void cross-sectional circumference in the (formula 1), and; as a second characteristic, in the void cross-sectional area in the catalyst layer, the average void radius, determined assuming that the void shape is a perfect circle, is 10 μm to 20 μm.
1. An exhaust gas purifying catalyst comprising a catalyst layer comprising two or more types of inorganic porous particles each having a different particle size, a catalytically active component, and voids, wherein;
as a first characteristic, the voids satisfying a condition of the following (formula 1) occupy 50% or more by number of all the voids in the catalyst layer:
L/ 2/(π S ) 1/2 ≧2 (formula 1)
wherein S represents a void cross-sectional area, and L represents a void cross-sectional circumference in the (formula 1), and;
as a second characteristic, in the void cross-sectional area in the catalyst layer, an average void radius, determined assuming that a void shape is a perfect circle, is 10 μm to 20 μm.
2. The exhaust gas purifying catalyst according to claim 1 , wherein voids each having a cross-sectional area of 1.96×10 3 μm 2 or more are present in an amount of 2.0 or more per a catalyst layer cross-sectional area of 1.0 ×10 4 μm 2 .