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

Patent metadata

Field	Value
Publication number	US-10065179-B2
Application number	US-201414910378-A
Country	US
Kind code	B2
Filing date	Aug 5, 2014
Priority date	Aug 9, 2013
Publication date	Sep 4, 2018
Grant date	Sep 4, 2018

Abstract

A ceria-zirconia-based composite oxide containing a composite oxide of ceria and zirconia is provided, in which primary particles having a particle diameter of 1.5 to 4.5 μm account for, on a particle number basis, at least 50% of all primary particles in the ceria-zirconia-based composite oxide, and the molar ratio of cerium to zirconium in the ceria-zirconia-based composite oxide is between 43:57 and 55:45.

First claim

What is claimed is:

1. A method for producing a ceria-zirconia-based composite oxide containing a composite oxide containing ceria and zirconia,
the method comprising:
providing a ceria-zirconia-based solid solution powder having a content ratio of cerium to zirconium in a range of 43:57 to 55:45 by mole ratio;
press-molding the ceria-zirconia-based solid solution powder under a pressure of 1,500 to 3,500 kgf/cm 2 ;
subjecting a ceria-zirconia-based solid solution powder compact to a first reducing treatment including 0.5 to 24 hours of heat treatment under reducing conditions at a temperature between 1,400 and 1,550° C.; and
subjecting the first reduction-treated ceria-zirconia-based solid solution powder compact to a second reducing treatment including 0.5 to 5 hours of heat treatment under reducing conditions at a temperature that is between 1,600 and 2,000° C. and at least 100° C. higher than the temperature in the first reducing treatment so as to obtain a ceria-zirconia-based composite oxide comprising a composite oxide containing ceria and zirconia, wherein
primary particles having a particle diameter of 1.5 to 4.5 μm in the ceria-zirconia-based composite oxide account for, on a particle number basis, at least 50% of all primary particles in the composite oxide, and a content ratio of cerium to zirconium in the ceria-zirconia-based composite oxide is in a range of 43:57 to 55:45 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)} and an intensity ratio of diffraction line at a 2θ of 28.5° to diffraction line at a 2θ of 29° {I(28/29)} satisfy requirement I(14/29)≥0.015 and I(28/29)≤0.08.

2. The method for producing a ceria-zirconia-based composite oxide according to claim 1 , further comprising, following the second reducing treatment, subjecting the ceria-zirconia-based composite oxide to oxidation treatment.

Assignees

• Toyota Motor Co Ltd
• Cataler Corp

Inventors

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

Classifications

• C04B2235/5463

  Particle size distributions · CPC title

• C04B2235/3229

  Cerium oxides or oxide-forming salts thereof · CPC title

• B01J23/63

  with rare earths or actinides · CPC title

• C04B35/50

  based on rare-earth compounds {(non-oxide rare earth compounds C04B35/5156)} · CPC title

• C04B2235/664

  Reductive annealing · CPC title