Pure perovskite phase rare earth ferrite porous hollow sphere, preparation method and application thereof

A ferrite and hollow sphere technology, applied in separation methods, chemical instruments and methods, dispersed particle separation, etc., can solve the problems of limited precious metal catalyst resources, poor reusability, and easy agglomeration and growth of precious metal nanoparticles. The preparation method is green, the NO conversion rate is high, and the N2 selectivity is good.

Inactive Publication Date: 2012-02-29
NANJING UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] 1. Precious metal catalyst resources are limited and expensive
[0005] 2. Under high temperature reaction, noble metal nanoparticles are easy to agglomerate and grow, the catalyst is easy to deactivate, the reusability is poor, and the regeneration of the catalyst is difficult

Method used

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  • Pure perovskite phase rare earth ferrite porous hollow sphere, preparation method and application thereof
  • Pure perovskite phase rare earth ferrite porous hollow sphere, preparation method and application thereof
  • Pure perovskite phase rare earth ferrite porous hollow sphere, preparation method and application thereof

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Effect test

preparation example Construction

[0033] (2) Preparation of porous hollow spheres of rare earth ferrite: put the rare earth / iron composite citric acid complex precursor in a tube furnace and calcinate at 700-900°C for 1-3 hours, and cool to room temperature to obtain rare earth ferrite Salt porous hollow sphere.

[0034] The product is used as a catalyst to catalyze the reduction of CO to NO to generate N 2 The reaction steps are as follows: Weigh 50 mg of catalyst and fill it into a vertical quartz tube column reactor, and place it in the middle of the vertical tube furnace. The catalyst was pretreated by heating to 100 °C for 1 hour under the protection of nitrogen atmosphere and then cooled to room temperature. Mix NO, CO and He at a volume ratio of 5:10:85 and pass them into a vertical quartz column reactor, keeping the space velocity at 24000h -1 . The quartz column reactor starts to heat, and the reaction product gas at different temperatures is extracted by 1cm 3 Pass through a gas chromatograph for...

Embodiment 1

[0036] In a 50 ml beaker, add 271 mg of La(NO 3 ) 3 ·6H 2 O and 252 mg of Fe(NO 3 ) 3 9H 2 O, add 25 milliliters of deionized water again, stir at room temperature for 30 minutes to make it dissolve completely. Then add 788 mg of citric acid monohydrate to the beaker, and continue to stir at room temperature for 30 minutes, then transfer the mixed solution to a 30 ml autoclave. After sealing, put the autoclave into an oven and react at 180°C for 24 hours. After naturally cooling to room temperature, the obtained product was washed three times with deionized water and absolute ethanol, respectively, and dried at 80° C. for 3 hours. The dried product was calcined in a tube furnace at 800°C for 2 hours, and cooled to room temperature to obtain porous hollow lanthanum ferrite spheres. Figure 1a is a scanning electron microscope photo of the product. It can be seen that the product is a spherical structure, the outer diameter of the ball is between 2 and 5 microns, and the s...

Embodiment 2

[0038] In a 50 ml beaker, add 217 mg of La(NO 3 ) 3 ·6H 2 O and 202 mg of Fe(NO 3 ) 3 9H 2 O, add 25 milliliters of deionized water again, stir at room temperature for 20 minutes to make it dissolve completely. Then add 630 mg of citric acid monohydrate into the beaker, and continue to stir at room temperature for 20 minutes, then transfer the mixed solution to a 30 ml autoclave. After sealing, put the autoclave into an oven and react at 180°C for 24 hours. After naturally cooling to room temperature, the obtained product was washed three times with deionized water and absolute ethanol, respectively, and dried at 80° C. for 3 hours. The dried product was calcined in a tube furnace at 800°C for 2 hours, and cooled to room temperature to obtain porous hollow lanthanum ferrite spheres.

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Abstract

The invention discloses a pure perovskite phase rare earth ferrite porous hollow sphere, a preparation method thereof and an application to the purification of vehicle exhaust, i.e., CO in exhaust is used for reducing NO in exhaust to generate N2 and CO2 so as to purify the vehicle exhaust. A synthesis method comprises the following steps of: adding ferric nitrate and rare earth nitrate of equal amount to de-ionized water, stirring at the room temperature to be dissolved, then adding a given amount of citric acid, stirring to be completely dissolved, then transferring to a high pressure reactor to be subject to heating reaction, washing and drying the product, and calcining in a pipe heater at high temperature to obtain the catalyst. The invention is prepared by the convenient hydrothermal synthesis method, and the obtained rare earth ferrite is of pure perovskite phase and is free of phase coexistence phenomenon and phase separation phenomenon; the preparation method has the advantages of environmental friendliness, convenience and strong universality; and in the reaction that CO reduces NO to generate N2 under the catalysis of the catalyst, the reaction temperature is low, the conversion rate of NO is high, the selectivity of N2 is good, and the catalysis performance can be comparable to the noble metal catalyst.

Description

technical field [0001] The invention relates to a pure perovskite phase rare earth ferrite porous hollow sphere catalyst, the preparation method of the catalyst and its application in purifying automobile exhaust gas, that is, using CO in the exhaust gas to reduce NO in the exhaust gas to generate N 2 and CO 2 , to achieve the purification of automobile exhaust. Background technique [0002] Rare earth ferrites are a class of multipurpose functional materials, which can be used as catalysts, gas sensors, magnetic materials, magneto-optical materials, etc. The traditional methods for synthesizing rare earth ferrites include high-temperature calcination mixed oxide method, sol-gel method, polyhydroxy complexation method, etc. The main disadvantage of these methods is that there are inevitably impurities such as spinel and garnet in the product. , or phase separation occurs. In recent years, it has been reported that rare earth ferrites in pure perovskite phase can be obtain...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01J23/83B01J35/10B01D53/94B01D53/62B01D53/56
Inventor 徐正李汛
Owner NANJING UNIV
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