Mitsui Minings & Melting Co., Ltd.

Honda Motor Co., Ltd.

Shingo Akita

Yoshinori Endo

Hiroki Kurihara

Yusuke Nagai

Takeshi Mori

Takayuki Watanabe

Tomoko Tsuyama

Yu Sakurada

Takeshi Nabemoto

An object of the present invention is to provide an exhaust gas purification catalyst including a wall-flow substrate and a catalyst layer, and having an improved exhaust gas purification performance, and, in order to achieve such an object, the present invention provides an exhaust gas purification catalyst including: a wall-flow substrate, first catalyst layers; and second catalyst layers; wherein the first catalyst layers and the second catalyst layers satisfy the following expressions (1) to (3):1<2  (1)1<2  (2)1>2  (3)wherein L1 represents the length of the first catalyst layers, L2 represents the length of the second catalyst layers, T1 represents the thickness of the rising portions of the first catalyst layers, T2 represents the thickness of the rising portions of the second catalyst layers, WC1 represents the mass of the first catalyst layers per unit volume of the portion of the substrate provided with the first catalyst layers, and WC2 represents the mass of the second catalyst layers per unit volume of the portion of the substrate provided with the second catalyst layers.

Exhaust gas purification catalyst

There is provided an exhaust gas purifying catalyst including a substrate and catalyst portions. The substrate includes an inflow-side cells, outflow-side cells, and porous partition walls, each partition wall separating the inflow-side cell from the outflow-side cell. The catalyst portion includes: (group A) first catalyst portions, each first catalyst portion being provided on a surface of the partition wall that faces the inflow-side cell on an upstream side in an exhaust gas flow direction; and (group B) second catalyst portions being provided on a surface of the partition wall that faces the outflow-side cell on a downstream side in the exhaust gas flow direction. Each catalyst portion of one of group A and group B includes at least one oxidizing catalyst layer and at least one reducing catalyst layer, and each catalyst portion of the other of group A and group B includes at least one oxidizing catalyst layer and/or at least one reducing catalyst layer.

A substrate () of an exhaust gas purification catalyst () includes inflow-side cells (), outflow-side cells (), and porous partition walls (), each separating the inflow-side cell and the outflow-side cell. Catalyst portions () are provided on the surfaces of the partition walls that each face the inflow-side cell and/or the surfaces of the partition walls that each face the outflow-side cell. In a cross section vertical to an exhaust gas flow direction, the percentage of the total area of voids, each void satisfying the expression L/{2(&#x3c0;S)}&#x2264;1.1 (wherein L is the perimeter of the void in the cross section, and S is the area of the void in the cross section), is greater than 10% to 30% or less based on the apparent area of the catalyst portion present on the partition wall. The content of zirconium element in terms of oxide (amount of ZrO) in the catalyst portions is from 35 mass % to 85 mass %.

A substrate () of an exhaust gas purification catalyst () includes inflow-side cells (), outflow-side cells (), and porous partition walls () each separating the inflow-side cell and the outflow-side cell. Catalyst portions () are provided on surfaces of the partition walls that each face the inflow-side cell and/or surfaces of the partition walls that each face the outflow-side cell. In a cross section vertical to an exhaust gas flow direction, the percentage of the total area of voids, each void satisfying the expression L/{2(&#x3c0;S)}&#x2264;1.1, wherein L is the perimeter of the void in the cross section and S is the area of the void in the cross section, is from 3 to 10% based on the apparent area of the catalyst portion present on the partition wall.

Exhaust gas purification catalyst and production method therefor

A substrate () of an exhaust gas purification catalyst () includes inflow-side cells (), outflow-side cells (), and porous partition walls (), each porous partition wall separating the cells () from each other. A first catalyst portions () is provided at least on a portion of a side of the partition wall () that faces the inflow-side cell (), the portion being located on an upstream side in an exhaust gas flow direction, and a second catalyst portion () is provided at least on a portion of a side of the partition wall that faces the outflow-side cell, the portion being located on a downstream side in the exhaust gas flow direction. A first pore volume is greater than a second pore volume, where the first pore volume is a pore volume of pores with a pore size of 10 &#x3bc;m to 18 &#x3bc;m, as measured on the first catalyst portions () and the partition walls () within a region where the first catalyst portions () are provided, and the second pore volume is a pore volume of pores with a pore size of 10 &#x3bc;m to 18 &#x3bc;m, as measured on the second catalyst portions () and the partition walls () within a region where the second catalyst portions () are provided. The first catalyst portion () exhibits the peak top of the pore size at between 20 nm and 500 nm.

In an exhaust gas purifying catalyst according to the present invention, a substrate includes inflow-side cells, outflow-side cells, and porous partition walls, each partition wall separating the inflow-side cell from the outflow-side cell. Catalyst portions include: first catalyst portions, each first catalyst portion being provided on a surface of the partition wall that faces the inflow-side cell on an upstream side in an exhaust gas flow direction, and second catalyst portions, each second catalyst portion being provided on a surface of the partition wall that faces the outflow-side cell on a downstream side, and the exhaust gas purifying catalyst satisfies the following expressions: I/I&#xd7;100&#x2265;60%, I/I&#xd7;100&#x2265;60%, I/I&#xd7;100&#x2265;3%, and I/I&#xd7;100&#x2265;3%, where I, I, I, I, and Irepresent pore volumes, definitions of which can be found in the specification.

A substrate () includes an inflow-side cell (), an outflow-side cell (), and a porous, gas-permeable partition wall () that separates the inflow-side cell () and the outflow-side cell () from each other, and also includes a first catalyst portion () that is provided on a side of the partition wall () that faces the inflow-side cell () at least at a portion in upstream side in an exhaust gas flow direction, and a second catalyst portion () that is provided on a side of the partition wall that faces the outflow-side cell at least at a portion in downstream side. With respect to a pore volume of pores with a pore size of 10 to 18 &#x3bc;m, when a measured value of the pore volume in the first catalyst portion () and the partition wall () within a region where the first catalyst portion () is provided is defined as a first pore volume, and a measured value of the pore volume in the second catalyst portion () and the partition wall () within a region where the second catalyst portion () is provided is defined as a second pore volume, the first pore volume is greater than the second pore volume. A catalytically active component contained in the first catalyst portion () and a catalytically active component contained in the second catalyst portion () are of different types.

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Saitama, Japan

Shingo Akita