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Metal oxide particle, production process thereof and exhaust gas purifying catalyst

A technology of oxides and metals, which is applied in the field of catalysts for exhaust gas purification, can solve the problems of not getting metal oxides, preventing sintering, and not necessarily obtaining the best effect of the mixture, and achieving a good interaction effect

Inactive Publication Date: 2007-05-30
TOYOTA JIDOSHA KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] In the above case of providing a metal oxide carrier comprising a plurality of materials and utilizing a combination of their properties, the plurality of metal oxide particles may be mixed, but if so mixed, a good combination of properties of these metal oxides may not be obtained, Because the combined metal oxide particles each have a large size
[0009] In addition, basically uniform metal oxide particles can be obtained from a sol obtained by mixing a variety of colloidal particles, but a uniform mixture may not necessarily achieve the best results
[0010] For example, composite metal oxides obtained by uniformly mixing ceria and zirconia are known to have good OSC and heat resistance, but sometimes ceria cannot fully exert its performance of preventing sintering of precious metals such as platinum
That is, both ceria and zirconia are present on the surface of this composite metal oxide, so a part of the precious metal is supported on the zirconia part instead of the ceria part, and thus sintering cannot be prevented

Method used

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  • Metal oxide particle, production process thereof and exhaust gas purifying catalyst

Examples

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Embodiment 1

[0065] In this example, metal oxide particles (cerium oxide (CeO 2 ): Zirconia (ZrO 2 ):barium oxide (BaO)=58:38:4 (weight ratio)), and platinum is supported on the metal oxide particles. The primary particle diameter of cerium oxide mainly constituting the surface layer was 29 nm, the primary particle diameter of zirconia mainly constituting the core was 47 nm, and the particle diameter of the obtained metal oxide particles was 5.8 μm.

[0066] Acid-stabilized ceria sol (116.0 g) (CeO 2 Content: 15% by weight, Needral, manufactured by Taki Chemical Co., Ltd., colloidal particle size: 29 nm, isoelectric point: pH8.5), 111.7 g of alkali-stabilized zirconia sol (ZrO 2 Content: 10.2% by weight, manufactured by Taki Chemical Co., Ltd., colloidal particle size: 47 nm, isoelectric point: pH 3.5) and 1.9 g of barium nitrate were mixed to make the mixed sol acidic and agglomerate zirconia.

[0067] Afterwards, ammonia (NH 3 ) aqueous solution, the pH is adjusted to 10, thereby cau...

Embodiment 2

[0070]In this example, metal oxide particles (ceria: zirconia: barium oxide = 58:38:4 (weight ratio)) including a core part containing more zirconia and a surface layer containing more ceria were obtained, And platinum is supported on the metal oxide particles. The primary particle diameter of cerium oxide mainly constituting the surface layer was 29 nm, the primary particle diameter of zirconia mainly constituting the core was 95 nm, and the particle diameter of the obtained metal oxide particles was 8.1 μm.

[0071] In addition to using 116.0g acid-stabilized cerium oxide sol (CeO 2 Content: 15% by weight, Needral, manufactured by Taki Chemical Co., Ltd., colloidal particle size: 29 nm), 97.4 g of alkali-stabilized zirconia sol (ZrO 2 A catalyst was obtained in the same manner as in Example 1 except that content: 11.7% by weight, colloidal particle diameter: 95 nm) and 1.9 g of barium nitrate were used as raw materials.

Embodiment 3

[0073] In this example, metal oxide particles (ceria: zirconia: barium oxide = 58:38:4 (weight ratio)) including a core part containing more zirconia and a surface layer containing more ceria were obtained, And platinum is supported on the metal oxide particles. The primary particle diameter of cerium oxide mainly constituting the surface layer was 5 nm, the primary particle diameter of zirconia mainly constituting the core was 47 nm, and the particle diameter of the obtained metal oxide particles was 5.4 μm.

[0074] In addition to using 114.4g acid stabilized cerium oxide sol (CeO 2 Content: 15.2% by weight, manufactured by Nissei Corp., colloidal particle size: 5 nm), 111.7 g of alkali-stabilized zirconia sol (ZrO 2 Content: 10.2% by weight, Ecolite, manufactured by Taki Chemical Co., Ltd., colloidal particle size: 47 nm) and 1.9 g of barium nitrate as raw materials, a catalyst was obtained in the same manner as in Example 1.

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Abstract

The present invention provides a metal oxide particle for a catalyst support comprising multiple species of metal oxides and capable of satisfactorily exerting the properties of the respective metal oxides, and also provide a production process therefor and an exhaust gas purifying catalyst obtained from this metal oxide particle. A metal oxide particle of the present invention comprises a core part 1 relatively rich in a first metal oxide and a surface layer 2 relatively rich in a second metal oxide, the core part and the surface layer each comprising a plurality of primary particles (1a, 2a), and the primary particle diameter of the second metal oxide being smaller than the primary particle diameter of the first metal oxide.

Description

technical field [0001] The present invention relates to metal oxide particles, a method for producing the same, and an exhaust gas-purifying catalyst produced from the metal oxide particles. Background technique [0002] Exhaust gases from internal combustion engines such as automobile engines contain nitrogen oxides (NO x ), carbon monoxide (CO), hydrocarbons (HC), etc. By being able to oxidize CO and HC while reducing NO x Catalysts for exhaust gas purification can remove these substances. As a representative catalyst for exhaust gas purification, a three-way catalyst obtained by supporting noble metals such as platinum (Pt), rhodium (Rh) and palladium (Pd) on a porous metal oxide carrier such as γ-alumina is known. [0003] Metal oxide supports can be formed from various materials, but in order to obtain a large surface area, alumina (Al 2 o 3 ). However, in recent years, in order to utilize the chemical properties of the carrier to promote the purification of exhau...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01G25/00C01G1/02B01D53/86B01D53/94B01J23/10B01J35/10F01N3/10B01J23/58B01J23/63B01J35/00B01J37/03
CPCB01J23/63B01J23/10C01G1/02C01P2004/64B01D53/945B82Y30/00B01D2255/407B01J35/0013B01D2255/9202C01G25/00B01D2255/9207Y02T10/22Y02T10/12B01J35/23
Inventor 三浦真秀久野央志
Owner TOYOTA JIDOSHA KK