Patent ID: 8546296

Claim:
An exhaust gas-purifying catalyst comprising: a substrate; and a first catalytic layer supported by the substrate, wherein the first catalytic layer includes: a first support made of alumina; a first oxygen storage material; an alkaline-earth metal and/or a compound of alkaline-earth metal selectively supported by a surface of the first support and dispersed on the surface of the first support; and a precious metal supported by the surface of the first support, wherein a ratio of a number of moles of the alkaline-earth metal in the first catalytic layer with respect to a volumetric capacity of the exhaust gas-purifying catalyst falls within a range of 0.0004 mol/L to 0.35 mol/L, wherein a correlation coefficient ρ Al,AE given by the following formula (1) is 0.79 or more, ρ Al , AE = C Al , AE σ Al ⁢ σ AE ( 1 ) wherein C Al,AE , σ Al , and σ AE in the formula (1) are represented by the following formulae (2), (3) and (4), respectively: C Al , AE = 1 350 ⁢ ∑ i = 1 350 ⁢ ( I Al , i - I Al , av ) ⁢ ( I AE , i - I AE , av ) ( 2 ) σ Al = 1 350 ⁢ ∑ i = 1 350 ⁢ ( I Al , i - I Al , av ) 2 ( 3 ) σ AE = 1 350 ⁢ ∑ i = 1 350 ⁢ ( I AE , i - I AE , av ) 2 ( 4 ) in the formulae (2) to (4), i is a natural number of 1 to 350, I Al,i is intensity of characteristic X-ray emitted by aluminum measured using an electron beam micro analyzer on the i-th intersection point among 350 intersection points of planes and a line, the planes dividing the catalytic layer into 351 equal parts arranged in the thickness direction, and the line being perpendicular to a main surface of the first catalytic layer, I Al,av is an arithmetic mean of the I Al,i given by the formula (5) below, I AE,i is intensity of characteristic X-ray emitted by the alkaline-earth metal element that is measured using the electron beam micro analyzer on the i-th intersection point, and I AE,av is an arithmetic mean of the I AE,i given by the following formula (6): I Al , av = 1 350 ⁢ ∑ i = 1 350 ⁢ I Al , i ( 5 ) I AE , av = 1 350 ⁢ ∑ i = 1 350 ⁢ I AE , i . ( 6 )