Complex oxide, method for producing same, and exhaust gas purifying catalyst

a technology of complex oxides and purifying catalysts, applied in the field of composite oxides, can solve the problems of reducing the efficiency of purifying exhaust gases, reducing the contact area, and reducing the pore volume, and achieves excellent heat resistance and catalytic activity, easy production, and large pore volume.

Inactive Publication Date: 2012-12-06
ANAN KASEI CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0011]It is an object of the present invention to provide a composite oxide which is capable of maintaining a large pore volume even in use in a high temperature environment, which brings about excellent heat resistance and catalytic activity, and which is particularly suitable for a co-catalyst for a catalyst for exhaust gas purification, as well as a catalyst for exhaust gas purification utilizing the composite oxide.
[0012]It is another object of the present invention to provide a method for producing a composite oxide which realizes easy production of the composite oxide of the present invention capable of maintaining a large pore volume even in use in a high temperature environment.

Problems solved by technology

This results in reduction of its pore volume, causing aggregation of the catalytic metals and decrease in the contact area between exhaust gas and the catalytic metals, which leads to reduction of efficiency in purifying exhaust gases.
Besides, the method disclosed in this publication does not provide a composite oxide having a larger volume of pores with a diameter of not larger than 200 nm after calcination at 900° C. for 5 hours, than the composite oxide taught in Patent Publication 1.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0064]This example relates to a composite oxide of cerium oxide and lanthanum oxide at a mass ratio of 90:10.

[0065]50 g of a ceric nitrate solution in terms of CeO2 containing not less than 90 mol % tetravalent cerium ions was measured out, and adjusted to a total amount of 1 L with pure water. The obtained solution was heated to 100° C., maintained at this temperature for 30 minutes, and allowed to cool down to the room temperature, to thereby obtain a cerium suspension.

[0066]After the mother liquor was removed from the cerium suspension thus obtained, 20.8 ml of a lanthanum nitrate solution (5.2 g in terms of La2O3) was added, and the total volume was adjusted to 1 L with pure water.

[0067]Then the cerium suspension containing a precursor of lanthanum oxide was maintained at 120° C. for 2 hours, allowed to cool, and neutralized to pH 8.5 with aqueous ammonia.

[0068]To a slurry resulting from the neutralization, an ammonium laurate solution prepared by dissolving 10.4 g of lauric aci...

example 2

[0070]This example relates to a composite oxide of cerium oxide and lanthanum oxide at a mass ratio of 85:15.

[0071]Composite oxide powder mainly composed of cerium oxide with 15% by mass of lanthanum oxide was prepared in the same way as in Example 1, except that the amount of the lanthanum nitrate solution was 33.2 ml (8.3 g in terms of La2O3). The properties of the composite oxide powder thus obtained were evaluated in the same way as in Example 1. The results are shown in Table 1.

example 3

[0072]This example relates to a composite oxide of cerium oxide and praseodymium oxide at a mass ratio of 90:10.

[0073]Composite oxide powder mainly composed of cerium oxide with 10% by mass of praseodymium oxide was prepared in the same way as in Example 1, except that the lanthanum nitrate solution was replaced with 20.5 ml of a praseodymium nitrate solution (5.2 g in terms of Pr6O11). The properties of the composite oxide powder thus obtained were evaluated in the same way as in Example 1. The results are shown in Table 1.

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Abstract

Disclosed are a composite oxide which is capable of maintaining a large volume of pores even used in a high temperature environment, and which has excellent heat resistance and catalytic activity, as well as a method for producing the composite oxide and a catalyst for exhaust gas purification employing the composite oxide. The composite oxide contains cerium and at least one element selected from aluminum, silicon, or rare earth metals other than cerium and including yttrium, at a mass ratio of 85:15 to 99:1 in terms oxides, and has a property of exhibiting a not less than 0.30 cm3/g, preferably not less than 0.40 cm3/g volume of pores with a diameter of not larger than 200 nm, after calcination at 900° C. for 5 hours, and is suitable for a co-catalyst in a catalyst for vehicle exhaust gas purification.

Description

FIELD OF ART[0001]The present invention relates to a composite oxide which may be used as a catalyst, functional ceramics, solid electrolyte for fuel cells, abrasive, and the like, particularly suitably used as a co-catalyst material in catalysts for purifying vehicle exhaust gas and the like, and which has a large pore volume, causing excellent catalytic performance, as well as to a method for producing the composite oxide and a catalyst for exhaust gas purification employing the composite oxide.BACKGROUND ART[0002]Catalysts for purifying vehicle exhaust gas and the like are composed of a catalytic metal such as platinum, palladium, or rhodium, and a co-catalyst for enhancing the catalyst action of such metal, both supported on a catalyst support made of, for example, alumina or cordierite. The co-catalyst material absorbs oxygen under the oxidizing atmosphere and desorbs oxygen under the reducing atmosphere, and functions to optimally maintain the air / fuel ratio so that the cataly...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B01J23/10C01F17/10C01F17/235C01F17/241
CPCB01D53/94C01P2006/16B01D2255/2063B01D2255/2065B01D2255/2066B01D2255/2068B01D2255/2092B01D2255/30B01D2255/9202B01D2257/404B01D2257/502B01D2257/702B01J23/10B01J23/63B01J35/1038B01J35/1042B01J35/1066B01J35/108B01J37/0018B01J37/0205B01J37/031B01J37/035C01F17/0018C01F17/0025C01F17/0043C01P2006/14B01D2255/2061C01F17/32C01F17/34C01F17/241C01F17/235C01F17/10B01D53/86C01F17/206C01F17/229B01J35/1052B01J37/088
Inventor OHTAKE, NAOTAKAYOKOTA, KAZUHIKO
Owner ANAN KASEI CO LTD
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