Exhaust gas purifying catalyst

Patent metadata

Field	Value
Publication number	US-2018236401-A1
Application number	US-201515534794-A
Country	US
Kind code	A1
Filing date	Dec 11, 2015
Priority date	Dec 12, 2014
Publication date	Aug 23, 2018
Grant date	—

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 lower layer of the 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

1 - 5 . (canceled)

6 . 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 an upper layer which contacts directly with an exhaust gas flowing into the catalyst, and a lower layer formed below the upper layer, the upper layer comprises a carrier and a 1st noble metal catalyst supported by the carrier, wherein the 1st noble metal catalyst contains at least Rh, the lower layer comprises a carrier, a 2nd noble metal catalyst supported by the carrier, and a ceria-zirconia composite oxide having a pyrochlore-type ordered array structure, wherein the 2nd noble metal catalyst contains at least Pt or Pd, 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.

7 . The exhaust gas purifying catalyst according to claim 6 , wherein the additional element contained in the ceria-zirconia composite oxide is praseodymium.

8 . The exhaust gas purifying catalyst according to claim 6 , wherein the lower layer contains the ceria-zirconia composite oxide in an amount ranges from 1 to 20 g/L in relation to the substrate volume.

9 . The exhaust gas purifying catalyst according to claim 7 , wherein the lower layer contains the ceria-zirconia composite oxide in an amount ranges from 1 to 20 g/L in relation to the substrate volume.

10 . The exhaust gas purifying catalyst according to claim 6 , 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; and another portion in which the lower layer is not formed at the downstream side end of the exhaust gas purifying catalyst.

11 . The exhaust gas purifying catalyst according to claim 7 , 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; and another portion in which the lower layer is not formed at the downstream side end of the exhaust gas purifying catalyst.

12 . The exhaust gas purifying catalyst according to claim 8 , 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; and another portion in which the lower layer is not formed at the downstream side end of the exhaust gas purifying catalyst.

13 . The exhaust gas purifying catalyst according to claim 9 , 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; and another portion in which the lower layer is not formed at the downstream side end of the exhaust gas purifying catalyst.

14 . The exhaust gas purifying catalyst according to claim 10 , 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.

15 . The exhaust gas purifying catalyst according to claim 11 , 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.

16 . The exhaust gas purifying catalyst according to claim 12 , 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.

17 . The exhaust gas purifying catalyst according to claim 13 , 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

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

Inventors

• Chinzei Isao
• Suzuki Hiromasa
• Yoshida Takeru
• Miura Masahide
• Aoki Yuki
• Okada Mitsuyoshi
• Tanabe Toshitaka
• Suda Akihiko
• Saito Yoshinori
• Ori Hirotaka
• Iizuka Kosuke
• Morikawa Akira

Classifications

• B01D2255/1021

  Platinum · CPC title

• C01P2002/36

  pyrochlore-type (A2B2O7) · CPC title

• B01J23/63

  with rare earths or actinides · CPC title

• B01J37/0244

  Coatings comprising several layers · CPC title

• B01J2523/00

  Constitutive chemical elements of heterogeneous catalysts · CPC title