Exhaust gas purification catalyst

An exhaust gas purifying catalyst comprising a substrate and catalyst portions provided in the substrate,

• the substrate including:
• an inflow-side cell which is a space having an open end on an inflow side thereof and a closed end on an outflow side thereof in an exhaust gas flow direction;
• an outflow-side cell which is a space having a closed end on an inflow side thereof and an open end on an outflow side thereof in the exhaust gas flow direction;
• and
• a porous partition wall separating the inflow-side cell from the outflow-side cell, and
• the catalyst portions including:
• a first catalyst portion provided at least on a part of a surface of the partition wall that faces the inflow-side cell;
• and
• a second catalyst portion provided at least on a part of a surface of the partition wall that faces the outflow-side cell,
• wherein one of the first catalyst portion or the second catalyst portion includes at least one oxidizing catalyst layer and at least one reducing catalyst layer,
• another one of the first catalyst portion or the second catalyst portion includes at least one oxidizing catalyst layer and/or at least one reducing catalyst layer,
• the oxidizing catalyst layer is a catalyst layer that contains an oxidation catalyst, the oxidizing catalyst layer contains or does not contain a reduction catalyst or catalytically active components other than the oxidation catalyst and the amount of the oxidation catalyst is larger than the total amount of the reduction catalyst and the catalytically active components other than the oxidation catalyst,
• the reducing catalyst layer is a catalyst layer that contains a reduction catalyst, the reducing catalyst layer contains or does not contain an oxidation catalyst or catalytically active components other than the reduction catalyst and the amount of the reduction catalyst is larger than the total amount of the oxidation catalyst and the catalytically active components other than the reduction catalyst, and
• the exhaust gas purifying catalyst has a structure I or II below:
• I:
• the first catalyst portion includes the oxidizing catalyst layer in direct contact with the partition wall that faces the inflow-side cell, and the reducing catalyst layer formed on a surface of the oxidizing catalyst layer, which is opposite to a surface of the oxidizing catalyst layer directly contacting the partition wall that faces the inflow-side cell, and the second catalyst portion includes the reducing catalyst layer in direct contact with the partition wall that faces the outflow-side cell;
• and
• II:
• the first catalyst portion includes the reducing catalyst layer in direct contact with the partition wall that faces the inflow-side cell, and the second catalyst portion includes the oxidizing catalyst layer in direct contact with the partition wall that faces the outflow-side cell, and the reducing catalyst layer formed on a surface of the oxidizing catalyst layer, which is opposite to a surface of the oxidizing catalyst layer directly contacting the partition wall that faces the outflow-side cell.