Exhaust gas purifying catalyst

Patent metadata

Field	Value
Publication number	US-10143968-B2
Application number	US-201515534805-A
Country	US
Kind code	B2
Filing date	Dec 11, 2015
Priority date	Dec 12, 2014
Publication date	Dec 4, 2018
Grant date	Dec 4, 2018

Abstract

The object of the present invention is to provide a high-performance exhaust gas purifying catalyst that can achieve oxygen absorption/release capacity and NOx purification performance. The object is solved by an exhaust gas purifying catalyst, which comprises a ceria-zirconia composite oxide having a pyrochlore-type ordered array structure in the upstream part of the catalyst coating layer, in which the ceria-zirconia composite oxide contains at least one additional element selected from the group consisting of praseodymium, lanthanum, and yttrium at 0.5 to 5.0 mol % of the total cation amount, and has a molar ratio of (cerium+the additional element):(zirconium) of 43:57 to 48:52.

First claim

The invention claimed is:

1. An exhaust gas purifying catalyst, which comprises a substrate and a catalyst coating layer formed on the substrate, wherein
the catalyst coating layer has: an upstream part occupying from an upstream side end of the exhaust gas purifying catalyst to a length within the range from 40% to 60% of the full length of the substrate; and a downstream part which is the remaining part of the catalyst coating layer;
wherein the upstream and downstream parts have different compositions,
the upstream part comprises a carrier, a 1st noble metal catalyst containing at least Pt or Pd that is supported by the carrier, and a ceria-zirconia composite oxide having a pyrochlore-type ordered array, and
the downstream part comprises a carrier and a 2nd noble metal catalyst containing at least Rh that is supported by the carrier, wherein
the ceria-zirconia composite oxide contains at least one additional element selected from the group consisting of praseodymium, lanthanum, and yttrium at 0.5 to 5.0 mol % in relation to the total cation amount, and the molar ratio of (cerium+the additional element):(zirconium) is within the range from 43:57 to 48:52.

2. The exhaust gas purifying catalyst according to claim 1 , wherein the additional element contained in the ceria-zirconia composite oxide is praseodymium.

3. The exhaust gas purifying catalyst according to claim 1 , wherein the content of the ceria-zirconia composite oxide in the upstream part is 1 to 20 g/L in relation to the volume of the substrate.

4. The exhaust gas purifying catalyst according to claim 2 , wherein the content of the ceria-zirconia composite oxide in the upstream part is 1 to 20 g/L in relation to the volume of the substrate.

Assignees

• Suzuki Hiromasa
• Yoshida Takeru
• Miura Masahide
• Chinzei Isao
• Okada Mitsuyoshi
• Tanabe Toshitaka
• Suda Akihiko
• Ori Hirotaka
• Chiba Akiya
• Iizuka Kosuke
• Morikawa Akira
• Toyota Motor Co Ltd
• Cataler Corp

Inventors

• Suzuki Hiromasa
• Yoshida Takeru
• Miura Masahide
• Chinzei Isao
• Okada Mitsuyoshi
• Tanabe Toshitaka
• Suda Akihiko
• Ori Hirotaka
• Chiba Akiya
• Iizuka Kosuke
• Morikawa Akira

Classifications

• C04B35/6261

  Milling · CPC title

• C04B2235/664

  Reductive annealing · CPC title

• B01J23/002

  Mixed oxides other than spinels, e.g. perovskite · CPC title

• C04B2235/3244

  Zirconium oxides, zirconates, hafnium oxides, hafnates, or oxide-forming salts thereof · CPC title

• B01D2255/2066

  Praseodymium · CPC title