Oxygen absorbing and releasing material, catalyst, exhaust gas purifying system, and exhaust gas treatment method

A catalyst and exhaust gas technology, applied in the field of oxygen absorption and release materials, can solve the problems of short honeycomb carrier length and short exhaust gas purification time, and achieve excellent NOx purification ability

Active Publication Date: 2020-07-03
NIPPON DENKO CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The catalyst washed and coated inside the honeycomb carrier is purified by contacting the circulating exhaust gas, but the overall length of the honeycomb carrier is short, ranging from 10 cm to 30 cm at most, and the time for purifying the exhaust gas is very short

Method used

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  • Oxygen absorbing and releasing material, catalyst, exhaust gas purifying system, and exhaust gas treatment method
  • Oxygen absorbing and releasing material, catalyst, exhaust gas purifying system, and exhaust gas treatment method
  • Oxygen absorbing and releasing material, catalyst, exhaust gas purifying system, and exhaust gas treatment method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0132] Adjust the ratio of zirconium oxychloride and cerium chloride to ZrO 2 : CeO 2 =17.5:7, ZrO 2 +CeO 2 Ammonium peroxodisulfate was added to an aqueous solution having a concentration of 40.8 g / L so as to be 15 g / L. While stirring the solution, the temperature was raised to 98° C. to cause precipitation of cerium / zirconium composite sulfate. The resulting solution was poured into 3.3% ammonia water so that the pH would be 8 or higher. The resulting precipitate was repeatedly filtered and washed five times with 2.5% ammonia water to obtain a cerium / zirconium composite hydroxide filter cake.

[0133] Add pure water to the obtained cerium / zirconium composite hydroxide filter cake to prepare ZrO 2 +CeO 2 A slurry with a concentration of 97g / L. Hydrochloric acid was added so that the pH of the slurry might become 6.5. Add cerium chloride solution, yttrium chloride solution, praseodymium chloride solution, gadolinium chloride solution to the obtained slurry to make mass...

Embodiment 2

[0137] As shown in Table 2, the compound composition is CeO 2 : ZrO2 : Y 2 o 3 : Pr 6 o 11 :Gd 2 o 3 =45:45:5:2.5:2.5 Except that, it carried out similarly to Example 1, and obtained the ceria / zirconia type composite oxide powder.

[0138] The obtained powder was measured for ion conductivity, OSC speed, and OSC amount in the same manner as in Example 1, and the results were 4.79×10 -5 S / cm, Δt 50 is 20.0 seconds, and the amount of OSC is 480 μmol-O 2 / g.

Embodiment 3

[0140] As shown in Table 2, the compound composition is CeO 2 : ZrO 2 : Y 2 o 3 :Gd 2 o 3 =45:45:5:5 Except that, it carried out similarly to Example 1, and obtained the ceria / zirconia type composite oxide powder.

[0141] The ion conductivity of the obtained powder was measured in the same manner as in Example 1, and the result was 4.3×10 -5 S / cm.

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Abstract

The purpose of the present invention is to provide: an oxygen absorbing and releasing material comprising a ceria/zirconia-based composite oxide having improved HC and NOx purification performance; and a three-way catalyst capable of reducing a NOx discharge amount. To solve said problem, the present invention provides an oxygen absorbing and releasing material, which is a ceria/zirconia-based composite oxide, containing 0.1-20 mol% (exclusive of 20 mol%) of Gd2O3 and has an ionic conductivity of 2*10-5 S/cm or more at 400 DEG C. In addition to the above, an oxygen absorbing and releasing material is provided which is characterized in that a molar ratio of cerium to zirconium is 0.2-0.6 in terms of cerium/(cerium+zirconium), and an oxygen absorbing and releasing speed (OSC speed) Delta t50is 20.0 seconds or more or an oxygen absorbing and releasing amount (OSC amount) is 300 [mu]mol-O2/g or more. Furthermore, by applying the oxygen absorbing and releasing material to a catalyst, it ispossible to obtain a catalyst which assists in the purification of exhaust gas that constantly changes according to the driving state and has a higher hazardous ingredient purification performance ofprecious metals than before. In particular, it is possible to obtain an automobile exhaust gas purification system having excellent CO, NOx and HC purification capacity.

Description

technical field [0001] The present invention relates to an oxygen absorbing and releasing material composed of ceria / zirconia composite oxide. In particular, it relates to an oxygen absorbing and releasing material having a high oxygen absorbing and releasing rate used as a co-catalyst in an exhaust gas purification catalyst. Further, it relates to a three-way catalyst comprising the above-mentioned oxygen absorbing and releasing material. Background technique [0002] Conventionally, a three-way catalyst has been used as a method for purifying carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx), which are harmful substances in exhaust gas from automobiles. The exhaust gas is purified by simultaneous oxidation of CO and HC and reduction of nitrogen oxides (NOx) using a three-way catalyst. As a three-way catalyst, noble metals (for example, Pt, Rh, Pd, Ir, Ru, etc.) The material is, for example, a refractory ceramic or metal honeycomb structure substrate, or...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01G25/00B01D53/94B01J23/63B01J32/00F01N3/10
CPCB01D53/94B01J23/63C01G25/00F01N3/10B01J23/44C01G25/006C01P2006/40C01P2006/12Y02T10/12B01J21/06B01J23/10C01G25/02B01J21/066B01J23/40B01J35/002B01J35/04F01N3/0835F01N3/0842F01N3/0857F01N3/101
Inventor 相原启吾伊藤智晴绀野博文长冈修平山田岳
Owner NIPPON DENKO CO LTD
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