Catalyst for purification of exhaust gas, method for producing the same, and method for purification of exhaust gas using the same

Patent metadata

Field	Value
Publication number	US-10112181-B2
Application number	US-201615553020-A
Country	US
Kind code	B2
Filing date	Feb 17, 2016
Priority date	Feb 27, 2015
Publication date	Oct 30, 2018
Grant date	Oct 30, 2018

Abstract

A catalyst for purification of exhaust gas, wherein a substrate and a catalyst coat layer which is formed on a surface of the substrate and which comprises catalyst particles, wherein the catalyst coat layer has an average thickness in a range of 25 to 160 μm, and a void fraction in a range of 50 to 80% by volume as measured by a weight-in-water method, 0.5 to 50% by volume of all voids in the catalyst coat layer consist of high-aspect ratio pores which have equivalent circle diameters in a range of 2 to 50 μm in a cross-sectional image of a cross-section of the catalyst coat layer which the cross-section is perpendicular to a flow direction of exhaust gas in the substrate, and which have aspect ratios of 5 or higher, and the high-aspect ratio pores have an average aspect ratio in a range of 10 to 50.

First claim

The invention claimed is:

1. A catalyst for purification of exhaust gas, comprising:
a substrate; and
a catalyst coat layer which is formed on a surface of the substrate and which comprises catalyst particles, wherein
the catalyst coat layer has an average thickness in a range of 25 to 160 μm, and a void fraction in a range of 50 to 80% by volume as measured by a weight-in-water method,
0.5 to 50% by volume of all voids in the catalyst coat layer consist of high-aspect ratio pores which have equivalent circle diameters in a range of 2 to 50 μm in a cross-sectional image of a cross-section of the catalyst coat layer which the cross-section is perpendicular to a flow direction of exhaust gas in the substrate, and which have aspect ratios of 5 or higher, and
the high-aspect ratio pores have an average aspect ratio in a range of 10 to 50.

2. The catalyst for purification of exhaust gas according to claim 1 , wherein
the high-aspect ratio pores are oriented such that a cumulative 80% angle value in an angle-based cumulative angle distribution of angles (cone angles) each formed by a vector in a long diameter direction and a vector in the flow direction of exhaust gas in the substrate is in a range of 0 to 45 degrees.

3. The catalyst for purification of exhaust gas according to claim 1 , wherein
0.6 to 40.9% by volume of all the voids in the catalyst coat layer consist of the high-aspect ratio pores, and
the high-aspect ratio pores have an average aspect ratio in a range of 10 to 35.

4. The catalyst for purification of exhaust gas according to claim 1 , wherein
particle diameters of the catalyst particles are such that a cumulative 15% diameter value in a cross-sectional area-based cumulative particle size distribution of the catalyst particles based on scanning electron microscope (SEM) observation of a cross-section of the catalyst coat layer is in a range of 3 to 10 μm.

5. The catalyst for purification of exhaust gas according to claim 1 , wherein
a coating amount of the catalyst coat layer is in a range of 50 to 300 g/L per unit volume of the substrate.

6. A method for producing a catalyst for purification of exhaust gas, comprising:
a step of obtaining a catalyst slurry by mixing metal oxide particles having a cumulative 50% diameter value in a range of 3 to 10 μm in a volume-based cumulative particle size distribution measured by laser diffractometry, a noble metal raw material, and a fibrous organic material having an average fiber diameter in a range of 1.7 to 8.0 μm and having an average aspect ratio in a range of 9 to 40 such that an amount of the fibrous organic material is in a range of 0.5 to 9.0 parts by mass relative to 100 parts by mass of the metal oxide particles;
a step of forming a catalyst slurry layer by applying the catalyst slurry onto a surface of a substrate such that a catalyst coat layer after calcination has an average thickness in a range of 25 to 160 μm; and
a calcination step of removing at least part of the fibrous organic material in the catalyst slurry layer to obtain a catalyst for purification of exhaust gas.

7. The method for producing a catalyst for purification of exhaust gas according to claim 6 , wherein
the fibrous organic material has an average fiber diameter in a range of 2.0 to 6.0 μm and an average aspect ratio in a range of 9 to 30.

8. The method for producing a catalyst for purification of exhaust gas according to claim 6 , wherein
in the step of forming a catalyst slurry layer, the catalyst slurry is applied onto the surface of the substrate such that a coating amount of the catalyst coat layer after the calcination is in a range of 50 to 300 g/L per unit volume of the substrate.

9. A method for purification of exhaust gas, comprising bringing exhaust gas emitted from an internal combustion engine into contact with the catalyst for purification of exhaust gas according to claim 1 to purify the exhaust gas.

Assignees

• Toyota Chuo Kenkyusho Kk
• Toyota Motor Co Ltd
• Cataler Corp

Inventors

• Katoh Satoru
• Tanabe Toshitaka
• Miura Masahide
• Suzuki Hiromasa
• Naito Hiroaki
• Ori Hirotaka
• Narita Keiichi
• Takeuchi Michihiko
• Ohashi Tatsuya

Classifications

• F01N2330/02

  Metallic plates or honeycombs, e.g. superposed or rolled-up corrugated or otherwise deformed sheet metal · CPC title

• B01D2255/407

  Zr-Ce mixed oxides · CPC title

• B01J37/0219

  the coating containing organic compounds · CPC title

• B01D53/94

  by catalytic processes · CPC title

• F01N3/28

  Construction of catalytic reactors · CPC title