EXHAUST GAS PURIFICATION CATALYST
An object of the present invention is to provide an exhaust gas purification catalyst including a substrate, a first catalyst layer provided on the substrate, and a second catalyst layer provided on an upside of the first catalyst layer, wherein the first catalyst layer contains Pd, wherein the second catalyst layer contains Rh, and wherein the exhaust gas purification catalyst can suppress a decrease in exhaust gas purification performance after exposure to a high temperature environment and a decrease in exhaust gas purification performance after exposure to phosphorus, and the present invention provides an exhaust gas purification catalyst ( 1 ) including a substrate ( 10 ), a first catalyst layer ( 20 ) provided on the substrate ( 10 ), and a second catalyst layer ( 30 ) provided on an upside of the first catalyst layer ( 20 ), wherein the first catalyst layer ( 20 ) contains Pd, and wherein the second catalyst layer contains Rh and a complex oxide containing Ce, Zr, and Al, wherein the exhaust gas purification catalyst ( 1 ) satisfies at least one of the following conditions A and B: (A) the first catalyst layer ( 20 ) contains Sr, and a content of Sr in terms of metal in the first catalyst layer ( 20 ) is 0.1% by mass or more, based on a mass of the first catalyst layer ( 20 ); and (B) the second catalyst layer ( 30 ) contains Sr, and a content of Sr in terms of metal in the second catalyst layer ( 30 ) is 0.1% by mass or more, based on a mass of the second catalyst layer ( 30 ).
1 . An exhaust gas purification catalyst, comprising a substrate, a first catalyst layer provided on the substrate, and a second catalyst layer provided on an upside of the first catalyst layer,
wherein the first catalyst layer comprises Pd,
wherein the second catalyst layer comprises Rh and a complex oxide comprising Ce, Zr, and Al, and
wherein the exhaust gas purification catalyst satisfies at least one of the following conditions A and B:
(A) the first catalyst layer comprises Sr, and a content of Sr in terms of metal in the first catalyst layer is 0.1% by mass or more, based on a mass of the first catalyst layer; and
(B) the second catalyst layer comprises Sr, and a content of Sr in terms of metal in the second catalyst layer is 0.1% by mass or more, based on a mass of the second catalyst layer.
2 . The exhaust gas purification catalyst according to claim 1 ,
wherein in the condition A, the content of Sr in terms of metal in the first catalyst layer is 0.1% by mass or more and 7.0% by mass or less, based on the mass of the first catalyst layer; and
wherein in the condition B, the content of Sr in terms of metal in the second catalyst layer is 0.1% by mass or more and 7.0% by mass or less, based on the mass of the second catalyst layer.
3 . The exhaust gas purification catalyst according to claim 2 ,
wherein in the condition A, the content of Sr in terms of metal in the first catalyst layer is 0.1% by mass or more and 4.0% by mass or less, based on the mass of the first catalyst layer; and
wherein in the condition B, the content of Sr in terms of metal in the second catalyst layer is 0.1% by mass or more and 4.0% by mass or less, based on the mass of the second catalyst layer.
4 . The exhaust gas purification catalyst according to claim 1 , wherein the complex oxide comprises La, and wherein a content of La in terms of La 2 O 3 in the complex oxide is 1.0% by mass or more, based on a mass of the complex oxide.
5 . The exhaust gas purification catalyst according to claim 1 ,
wherein, in a case where the exhaust gas purification catalyst satisfies the condition A, the exhaust gas purification catalyst satisfies following condition C:
(C) a ratio of the content of Sr in terms of metal in the first catalyst layer based on the mass of the first catalyst layer to a content of the complex oxide in the second catalyst layer based on the mass of the second catalyst layer is 0.0010 or more and 0.0800 or less; and
wherein, in a case where the exhaust gas purification catalyst satisfies the condition B, the exhaust gas purification catalyst satisfies following condition D:
(D) a ratio of the content of Sr in terms of metal in the second catalyst layer based on the mass of the second catalyst layer to a content of the complex oxide in the second catalyst layer based on the mass of the second catalyst layer is 0.0010 or more and 0.0800 or less.
6 . The exhaust gas purification catalyst according to claim 1 , wherein a content of the complex oxide in the second catalyst layer is 80.0% by mass or more, based on the mass of the second catalyst layer.
7 . The exhaust gas purification catalyst according to claim 1 , wherein a content of Al in terms of Al 2 O 3 in the complex oxide is 30.0% by mass or more and 60.0% by mass or less, based on a mass of the complex oxide.
8 . The exhaust gas purification catalyst according to claim 1 , wherein the exhaust gas purification catalyst satisfies at least the condition A of the conditions A and B.