Catalyst for purifying exhaust gases

A technology of catalyst and exhaust outlet, applied in the field of catalyst for purifying exhaust gas and three-way catalyst, which can solve problems such as the decline of Rh characteristics

Inactive Publication Date: 2007-08-08
TOYOTA JIDOSHA KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Disadvantages that the formation of alloys may lead to a decrease in the properties of Rh

Method used

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  • Catalyst for purifying exhaust gases
  • Catalyst for purifying exhaust gases
  • Catalyst for purifying exhaust gases

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] 1 and 2 show a catalyst for purifying exhaust gas according to Embodiment 1 of the present invention. As shown in the figure, the catalyst includes a cylindrical honeycomb substrate 1 and a catalyst supporting layer 2 . Cylindrical honeycomb matrix 1 includes a large number of square cells, and has a total length L of 130mm 1 . The catalyst supporting layer 2 is formed on the surface of the square cells of the cylindrical honeycomb base 1 . Note that the coexistence region 20 is formed at a length L from the exhaust gas inlet end of the cylindrical honeycomb base 1 toward the exhaust gas outlet end. 2 The rhodium region 21 is formed in the second range starting from the coexistence region 20 toward the exhaust gas outlet end with a length of 110 mm.

[0039] The production process of the catalyst according to Example 1 will be described in detail below without describing the detailed arrangement.

[0040] 120 parts by weight of CeO 2 -ZrO 2 The solid solution powd...

Embodiment 2

[0044] The catalyst for purifying exhaust gas according to Example 2 of the present invention is prepared in the same manner as in Example 1, but the difference is that the coexistence region 20 consists of a length L of 10 mm from the exhaust gas inlet end. 2 Formed, and accordingly, the loading amount of Pt in the coexistence region 20 was 20 g / lL of the honeycomb substrate 1 . Note that the total loading of Pt is 1.666 g.

Embodiment 3

[0046] The catalyst for purifying exhaust gas according to Example 3 of the present invention is prepared in the same manner as Example 1, but the difference is that the coexistence region 20 consists of a length L of 50 mm from the exhaust gas inlet end. 2 Formed, and accordingly, the loading amount of Pt in the coexistence region 20 was 4 g / lL of the honeycomb matrix 1 . Note that the total loading of Pt is 1.666 g.

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Abstract

A catalyst for purifying exhaust gases includes a support substrate, and a catalytic loading layer. The support substrate demarcates an exhaust-gas flow passage, an exhaust-gas inlet end and an exhaust-gas outlet end, and has an overall length between the exhaust-gas inlet end and the exhaust-gas outlet end. The catalytic loading layer is formed on a surface of the exhaust-gas flow passage, and is composed of a porous oxide support and a noble metal. The catalytic loading layer includes a coexistence area, and a rhodium area. The coexistence area occupies the overall length of the support substrate by a factor of 4 / 10 or less from the exhaust-gas inlet end, and is composed of rhodium and platinum loaded thereon. The rhodium area is formed toward the exhaust-gas outlet end from the coexistence area, and is composed of rhodium loaded uniformly thereon in a flow direction of the exhaust gases.

Description

technical field [0001] The present invention relates to catalysts for purifying exhaust gases such as HC, CO and NO in exhaust gases x three-way catalyst. In particular, the present invention relates to a catalyst for purifying exhaust gas that is excellent in HC purification performance in a low-temperature region such as exhaust gas discharged immediately after engine startup. Background technique [0002] Conventionally, three-way catalysts have been widely used as exhaust gas purification catalysts for purification of exhaust gas from motor vehicles. Three-way catalysts include a porous support such as alumina and a noble metal such as Pt supported on the porous support. Three-way catalyst can purify HC, CO and NO at approximately stoichiometric air-fuel ratio x . [0003] Among noble metals, Pt and Pd are mainly used to purify CO and HC by oxidation. Rh is not only mainly used to purify NO by reduction x , but also has the effect of preventing Pt and Pd from sinte...

Claims

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Application Information

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Patent Type & AuthorityApplications(China)
IPC IPC(8): B01D53/94B01J35/00F01N3/28
CPCB01D2255/908B01J23/63F01N2330/06B01J23/40B01D2255/206B01J23/464B01D2255/102B01J35/0006B01D53/945F01N3/2828B01J37/0242Y02T10/22Y02T10/12B01J35/19B01D53/94B01D39/00
Inventor铃木宏昌
OwnerTOYOTA JIDOSHA KK