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US 8,796,172 B2Granted
Exhaust gas purification catalyst
AssigneeToyota Jidosha Kabushiki Kaisha
InventorIsao Chinzei
Life of this patent
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Abstract
An exhaust gas purification catalyst is provided with a catalyst coating layer (40) formed on the surface of a substrate (32). This catalyst coating layer (40) is formed of an upper catalyst coating layer (36) in which Rh particles are supported on a porous support, and a lower catalyst coating layer (34) in which Pd particles are supported on a support that contains an ACZ composite oxide made of alumina (Al2O3), ceria (CeO2), and zirconia (ZrO2).
Claims10
An exhaust gas purification catalyst, comprising:
- a substrate;
- a catalyst coating layer that is formed of a porous support and is formed on a surface of the substrate;
- and
- a noble metal catalyst that is supported on the porous support of the catalyst coating layer,
- wherein:
- the catalyst coating layer is formed as a layer structure having an upper layer relatively farther from the substrate surface and a lower layer relatively closer to the substrate surface;
- Rh particles are supported as the noble metal catalyst in the upper layer;
- Pd particles are supported as the noble metal catalyst in the lower layer;
- the porous support of the lower layer that supports the Pd particles is formed by an ACZ composite oxide made of alumina (Al2O3), ceria (CeO2), and zirconia (ZrO2);
- the ACZ composite oxide is produced by an alkoxide method;
- starting materials in the alkoxide method are a metal alkoxide and a metal salt;
- Al, Ce, and Zr are all converted into the metal alkoxide, or at least one of Al, Ce, and Zr is converted into the metal alkoxide;
- the metal salt is used for components other than the metal alkoxide;
- the starting materials are dissolved in a solvent and mixed and hydrolysis and polycondensation reactions are carried out, after which the ACZ composite oxide is obtained by a heat treatment;
- the ACZ composite oxide produced by the alkoxide method is a composite oxide in which the Al, Ce, and Zr become almost uniformly mixed at the atomic or oxide molecular level;
- and
- a Ce/Zr atomic ratio in the ACZ composite oxide is not more than 0.6.
14 more elements
An exhaust gas purification catalyst, comprising:
- a substrate;
- a catalyst coating layer that is formed of a porous support and is formed on a surface of the substrate;
- and
- a noble metal catalyst that is supported on the porous support of the catalyst coating layer,
- wherein:
- the catalyst coating layer is formed as a layer structure having an upper layer relatively farther from the substrate surface and a lower layer relatively closer to the substrate surface;
- Rh particles are supported as the noble metal catalyst in the upper layer;
- Pd particles are supported as the noble metal catalyst in the lower layer;
- the porous support of the lower layer that supports the Pd particles is formed by an ACZ composite oxide made of alumina (Al2O3), ceria (CeO2), and zirconia (ZrO2);
- the ACZ composite oxide is produced by an alkoxide method;
- starting materials in the alkoxide method are a metal alkoxide and a metal salt;
- Al, Ce, and Zr are all converted into the metal alkoxide, or at least one of Al, Ce, and Zr is converted into the metal alkoxide;
- the metal salt is used for components other than the metal alkoxide;
- the starting materials are dissolved in a solvent and mixed and hydrolysis and polycondensation reactions are carried out, after which the ACZ composite oxide is obtained by a heat treatment;
- the ACZ composite oxide produced by the alkoxide method is a composite oxide in which the Al, Ce, and Zr become almost uniformly mixed at the atomic or oxide molecular level;
- and
- primary particles in the ACZ composite oxide have an average particle diameter of not more than 10 nm and a specific surface area of at least 30 m2/g.
14 more elements
An exhaust gas purification catalyst, comprising:
- a substrate;
- a catalyst coating layer that is formed of a porous support and is formed on a surface of the substrate;
- and
- a noble metal catalyst that is supported on the porous support of the catalyst coating layer,
- wherein:
- the catalyst coating layer is formed as a layer structure having an upper layer relatively farther from the substrate surface and a lower layer relatively closer to the substrate surface;
- Rh particles are supported as the noble metal catalyst in the upper layer;
- Pd particles are supported as the noble metal catalyst in the lower layer;
- the porous support of the lower layer that supports the Pd particles is formed by an ACZ composite oxide made of alumina (Al2O3), ceria (CeO2), and zirconia (ZrO2);
- the ACZ composite oxide is produced by an alkoxide method;
- starting materials in the alkoxide method are a metal alkoxide and a metal salt;
- Al, Ce, and Zr are all converted into the metal alkoxide, or at least one of Al, Ce, and Zr is converted into the metal alkoxide;
- the metal salt is used for components other than the metal alkoxide;
- the starting materials are dissolved in a solvent and mixed and hydrolysis and polycondensation reactions are carried out, after which the ACZ composite oxide is obtained by a heat treatment;
- the ACZ composite oxide produced by the alkoxide method is a composite oxide in which the Al, Ce, and Zr become almost uniformly mixed at the atomic or oxide molecular level;
- the porous support of the upper layer that supports the Rh particles is formed by a mixture of alumina and a CZ composite oxide made of ceria and zirconia;
- and
- a Ce/Zr atomic ratio in the CZ composite oxide is at least 0.5.
15 more elements
Dependencies are inferred from the claim text.