Ceria-zirconia-based composite oxide and method for producing same, and catalyst for exhaust gas purification including ceria-zirconia-based composite oxide

Patent metadata

Field	Value
Publication number	US-9931614-B2
Application number	US-201414897940-A
Country	US
Kind code	B2
Filing date	Jun 12, 2014
Priority date	Jun 13, 2013
Publication date	Apr 3, 2018
Grant date	Apr 3, 2018

Abstract

A ceria-zirconia-based composite oxide including a composite oxide containing ceria and zirconia, wherein the ceria-zirconia-based composite oxide contains at least one member selected from the group consisting of praseodymium, lanthanum, and yttrium in an amount of 0.5 to 5.0 mol % relative to a total amount of the cations contained in the ceria-zirconia-based composite oxide, where the ratio of the content of both cerium and the at least one member selected from the group consisting of praseodymium, lanthanum, and yttrium in the ceria-zirconia-based composite oxide to the content of zirconium therein ([cerium and the at least one member selected from the group consisting of praseodymium, lanthanum, and yttrium]:[zirconium]) is in the range of 43:57 to 48:52 by mole ratio.

First claim

The invention claimed is:

1. A ceria-zirconia-based composite oxide comprising:
a composite oxide containing ceria and zirconia, wherein
the ceria-zirconia-based composite oxide contains at least one member selected from the group consisting of praseodymium, lanthanum, and yttrium in an amount of 0.5 to 5.0 mol % relative to a total amount of cations contained in the ceria-zirconia-based composite oxide,
where a ratio of a content of both cerium and the at least one member selected from the group consisting of praseodymium, lanthanum, and yttrium to a content of zirconium in the ceria-zirconia-based composite oxide therein ([cerium and the at least one member selected from the group consisting of praseodymium, lanthanum, and yttrium]:[zirconium]) is in a range of 43:57 to 48:52 by mole ratio, and
when heated for 5 hours in the atmosphere under a temperature condition of 1,100° C. and thereafter examined by X-ray diffractometry using CuKα, the ceria-zirconia-based composite oxide exhibits an X-ray diffraction pattern in which an intensity ratio of diffraction line at a 2θ of 14.5° to diffraction line at a 2θ of 29° {I(14/29) value} and an intensity ratio of diffraction line at a 2θ of 28.5° to diffraction line at a 2θ of 29° {I(28/29) value} satisfy the following conditions:
I(14/29) value≥0.02; and
I(28/29) value≤0.08.

2. A method for producing a ceria-zirconia-based composite oxide according to claim 1 ,
the method comprising:
preparing a ceria-zirconia-based solid-solution powder that contains at least one member selected from the group consisting of praseodymium, lanthanum, and yttrium in an amount of 0.5 to 5.0 mol % relative to a total cation amount, a ratio of a content of both cerium and the at least one member selected from the group consisting of praseodymium, lanthanum, and yttrium to a content of zirconium ([cerium and the at least one member selected from the group consisting of praseodymium, lanthanum, and yttrium]:[zirconium]) being in a range of 43:57 to 48:52 by mole ratio;
press-molding the ceria-zirconia-based solid-solution powder at a pressure of 400 to 3,500 kgf/cm 2 ; and
subjecting, after the press molding, the ceria-zirconia-based solid-solution powder to a reduction treatment under temperature conditions of 1,450 to 2,000° C. to obtain the ceria-zirconia-based composite oxide, wherein the ceria-zirconia-based composite oxide, when heated for 5 hours in the atmosphere under a temperature condition of 1,100° C. and thereafter examined by X-ray diffractometry using CuKα, exhibits an X-ray diffraction pattern in which an intensity ratio of diffraction line at a 2θ of 14.5° to diffraction line at a 2θ of 29° {I(14/29) value} and an intensity ratio of diffraction line at a 2θ of 28.5° to diffraction line at a 2θ of 29° {I(28/29) value} satisfy the following conditions:
I(14/29) value≥0.02; and
I(28/29) value≤0.08.

3. The method for producing a ceria-zirconia-based composite oxide according to claim 2 , further comprising
subjecting, after the reduction treatment, the ceria-zirconia-based composite oxide to an oxidation treatment.

4. A catalyst for exhaust gas purification, comprising
a ceria-zirconia-based composite oxide produced according to the method of claim 2 .

5. A catalyst for exhaust gas purification, comprising
the ceria-zirconia-based composite oxide according to claim 1 .

Assignees

• Toyota Motor Co Ltd
• Cataler Corp

Inventors

• Morikawa Akira
• Konishi Kae
• Tanabe Toshitaka
• Suda Akihiko
• Miura Masahide
• Suzuki Hiromasa
• Chinzei Isao
• Chiba Akiya
• Iizuka Kosuke

Classifications

• B01J23/10 Primary

  of rare earths · CPC title

• C01P2002/50

  Solid solutions · CPC title

• C01P2004/61

  Micrometer sized, i.e. from 1-100 micrometer · CPC title

• B01J37/16

  Reducing · CPC title

• C01P2006/12

  Surface area · CPC title