Exhaust gas purifying catalyst

Patent metadata

Field	Value
Publication number	US-10556223-B2
Application number	US-201515534841-A
Country	US
Kind code	B2
Filing date	Dec 11, 2015
Priority date	Dec 12, 2014
Publication date	Feb 11, 2020
Grant date	Feb 11, 2020

Abstract

The object of the present invention is to provide an exhaust gas purifying catalyst that can achieve high purification performance while suppressing H 2 S emissions. The object is solved by an exhaust gas purifying catalyst in which the top layer of a catalyst coating layer comprises a ceria-zirconia composite oxide having a pyrochlore-type ordered array structure, 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 % in relation to the total cation amount, and the molar ratio of (cerium+additional element):(zirconium) is within the range from 43:57 to 48:52.

First claim

The invention claimed is:

1. An exhaust gas purifying catalyst comprising a substrate and a catalyst coating layer formed on the substrate, wherein
the catalyst coating layer at least has a lower layer and an upper layer, wherein the upper layer contacts directly with an exhaust gas flowing into the catalyst,
the lower layer comprises a carrier and a first noble metal catalyst supported by the carrier, wherein the first noble metal catalyst contains at least Pt or Pd,
the upper layer comprises a carrier, a second noble metal catalyst supported by the carrier, and a ceria-zirconia composite oxide having a pyrochlore ordered array structure, wherein the second noble metal catalyst contains at least Rh,
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+additional element):(zirconium) is within the range from 43:57 to 48:52; and
wherein the catalyst coating layer has:
a portion in which the upper layer is not formed at the upstream side end of the exhaust gas purifying catalyst;
a portion in which the upper layer is formed on the lower layer; and
a portion in which the lower layer is not formed at the downstream side end of the exhaust gas purifying catalyst.

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 upper layer contains the ceria-zirconia composite oxide in an amount ranges from 1 to 20 g/L in relation to the substrate volume.

4. The exhaust gas purifying catalyst according to claim 2 , wherein the upper layer contains the ceria-zirconia composite oxide in an amount ranges from 1 to 20 g/L in relation to the substrate volume.

5. The exhaust gas purifying catalyst according to claim 1 , wherein
the lower layer is formed over the area whose length is within the range from 75% to 85% of the total length of the substrate from the upstream side end of the exhaust gas purifying catalyst, and
the upper layer is formed over the area whose length is within the range from 75% to 85% of the total length of the substrate from the downstream side end of the exhaust gas purifying catalyst.

Assignees

• Suzuki Hiromasa
• Yoshida Takeru
• Miura Masahide
• Aoki Yuki
• Chinzei Isao
• Saito Yoshinori
• Ochiai Daisuke
• Okada Mitsuyoshi
• Tanabe Toshitaka
• Suda Akihiko
• Sato Masanao
• Chiba Akiya
• Morikawa Akira
• Ori Hirotaka
• Toyota Motor Co Ltd
• Cataler Corp

Inventors

• Suzuki Hiromasa
• Yoshida Takeru
• Miura Masahide
• Aoki Yuki
• Chinzei Isao
• Saito Yoshinori
• Ochiai Daisuke
• Okada Mitsuyoshi
• Tanabe Toshitaka
• Suda Akihiko
• Sato Masanao
• Chiba Akiya
• Morikawa Akira
• Ori Hirotaka

Classifications

• B01D2258/014

  Stoichiometric gasoline engines · CPC title

• B01D2255/2061

  Yttrium · CPC title

• B01J37/08

  Heat treatment {(B01J37/0009, B01J37/0018 take precedence)} · CPC title

• B01D2255/1021

  Platinum · CPC title

• C01P2002/50

  Solid solutions · CPC title