Exhaust gas purification catalyst

Patent metadata

Field	Value
Publication number	US-11534737-B2
Application number	US-201916965806-A
Country	US
Kind code	B2
Filing date	Jan 16, 2019
Priority date	Feb 15, 2018
Publication date	Dec 27, 2022
Grant date	Dec 27, 2022

Abstract

An exhaust gas purification catalyst including particles of a catalyst metal supported on secondary particles of an inorganic oxide, wherein when scanning transmission electron microscope-energy dispersive X-ray line analysis is performed from a surface of the secondary particles toward a center thereof, a support density of the catalyst metal on a surface side of the secondary particles is greater than the support density of the catalyst metal in a center part of the secondary particles.

First claim

The invention claimed is:

1. An exhaust gas purification catalyst comprising particles of a catalyst metal supported on secondary particles of an inorganic oxide, wherein when scanning transmission electron microscope-energy dispersive X-ray line analysis is performed from a surface of the secondary particles toward a center thereof, a support density of the catalyst metal on a surface side of the secondary particles is greater than the support density of the catalyst metal in a center part of the secondary particles, wherein
an average particle diameter of the secondary particles is more than 1.5 μm, and
80% or more of the catalyst metal is supported within a range of 600 nm from the surface of the secondary particles.

2. An exhaust gas purification catalyst comprising particles of a catalyst metal supported on secondary particles of an inorganic oxide, wherein
when scanning transmission electron microscope-energy dispersive X-ray line analysis is performed from a surface of the secondary particles toward a center thereof, a support density of the catalyst metal on a surface side of the secondary particles is greater than the support density of the catalyst metal in a center part of the secondary particles, wherein
an average particle diameter of the secondary particles is more than 1.0 μm, and
80% or more of the catalyst metal is supported within a range of 400 nm from the surface of the secondary particles.

3. The exhaust gas purification catalyst according to claim 1 , wherein the catalyst metal is one or more metals selected from platinum-group metals, copper-group metals, and iron-group metals.

4. The exhaust gas purification catalyst according to claim 1 , wherein the inorganic oxide is an oxide comprising one or more selected from alumina, ceria, and zirconia.

5. An exhaust gas purification catalyst device, comprising:
a substrate and a catalyst coating layer on the substrate, wherein
the catalyst coating layer comprises the exhaust gas purification catalyst according to claim 1 .

6. A method for the production of the exhaust gas purification catalyst according to claim 1 , comprising the steps of:
immersing carrier particles in a metal-supporting formulation coating liquid, and
firing the carrier particles after immersion in the coating liquid, wherein
the carrier particles are composed of secondary particles of an inorganic oxide,
the metal-supporting formulation coating liquid comprises precursor particles composed of a metal precursor and an organic compound having a mercapto group and a carboxyl group,
the metal precursor is a hydroxide containing a metal atom or Pt(NO 2 ) 2 (NH 3 ) 2 , and
a usage rate of the organic compound having a mercapto group and a carboxyl group is 7 mol or more and 50 mol or less per mol of the metal precursor mixed in the coating liquid.

7. The method according to claim 6 , wherein the organic compound is one or more selected from thioglycolic acid, thiolactic acid, 2-mercaptosuccinic acid, 2,3-dimercaptosuccinic acid, 3-mercaptopropionic acid, 3-mercaptoisobutyric acid, N-acetylcysteine, penicillamine, and thiosalicylic acid.

8. The method according to claim 6 , wherein a compounding amount of the organic compound in the metal-supporting formulation coating liquid is 10 mol to 40 mol per mol of the metal precursor.

9. The method according to claim 6 , wherein the precursor particles are formed by coordinating the sulfur atoms in the mercapto groups of the organic compound with the metal atoms in the metal precursor.

10. The method according to claim 6 , wherein the average particle diameter of the precursor particles, as a median diameter determined by dynamic light scattering photometry, is 0.7 nm to 10.0 nm.

11. The exhaust gas purification catalyst according to claim 2 , wherein the catalyst metal is one or more metals selected from platinum-group metals, copper-group metals, and iron-group metals.

12. The exhaust gas purification catalyst according to claim 2 , wherein the inorganic oxide is an oxide comprising one or more selected from alumina, ceria, and zirconia.

13. An exhaust gas purification catalyst device, comprising:
a substrate and a catalyst coating layer on the substrate, wherein
the catalyst coating layer comprises the exhaust gas purification catalyst according to claim 2 .

14. A method for the production of the exhaust gas purification catalyst according to claim 2 , comprising the steps of:
immersing carrier particles in a metal-supporting formulation coating liquid, and
firing the carrier particles after immersion in the coating liquid, wherein
the carrier particles are composed of secondary particles of an inorganic oxide, and
the metal-supporting formulation coating liquid comprises precursor particles composed of a metal precursor and an organic compound having a mercapto group and a carboxyl group,
the metal precursor is a hydroxide containing a metal atom or Pt(NO 2 ) 2 (NH 3 ) 2 , and
a usage rate of the organic compound having a mercapto group and a carboxyl group is 7 mol or more and 50 mol or less per mol of the metal precursor mixed in the coating liquid.

15. The method according to claim 14 , wherein the organic compound is one or more selected from thioglycolic acid, thiolactic acid, 2-mercaptosuccinic acid, 2,3-dimercaptosuccinic acid, 3-mercaptopropionic acid, 3-mercaptoisobutyric acid, N-acetylcysteine, penicillamine, and thiosalicylic acid.

16. The method according to claim 14 , wherein a compounding amount of the organic compound in the metal-supporting formulation coating liquid is 10 mol to 40 mol per mol of the metal precursor.

17. The method according to claim 14 , wherein the precursor particles are formed by coordinating the sulfur atoms in the mercapto groups of the organic compound with the metal atoms in the metal precursor.

18. The method according to claim 14 , wherein the average particle diameter of the precursor particles, as a median diameter determined by dynamic light scattering photometry, is 0.7 nm to 10.0 nm.

Assignees

• Cataler Corp

Inventors

• Nihashi Hiroki

Classifications

• B01J37/0221

  of particles · CPC title

• B01J23/464 Primary

  Rhodium · CPC title

• F01N2510/06

  for exhaust purification, e.g. catalytic reaction · CPC title

• B01J37/0213

  Preparation of the impregnating solution · CPC title

• Y02T10/12

  Improving ICE efficiencies · CPC title