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Core-shell structure magnetic microsphere aluminum oxide and method for preparing the same

A spherical alumina, core-shell structure technology, applied in chemical instruments and methods, metal/metal oxide/metal hydroxide catalysts, catalyst carriers, etc., can solve the problems of poor magnetic properties and low content of magnetic substances

Inactive Publication Date: 2008-01-30
BEIJING UNIV OF CHEM TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In addition, in order to completely cover the dispersed magnetic cores inside the alumina during the molding process, the amount of magnetic cores added is restricted, resulting in a low content of magnetic substances in the carrier and poor magnetic properties.

Method used

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  • Core-shell structure magnetic microsphere aluminum oxide and method for preparing the same

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] Step A: Weigh 3.49g Ni(NO) at a molar ratio of 3:5:2 3 ) 2 ·6H 2 O, 3.98g FeCl 2 ·4H 2 O and 3.23gFe(NO 3 ) 3 ·9H 2 Dissolve O in 40ml and remove O 2 Mixed salt solution in deionized water; weigh 2.40g NaOH and 2.97g anhydrous Na 2 CO 3 Dissolve in 40ml de O 2 Prepare mixed alkali solution in deionized water; in N 2 Under the protection, slowly drip the mixed alkaline solution into the mixed salt solution. When the pH value in the system reaches 7, stop the dripping. 2 Stir and crystallize in a water bath at 40°C for 17 hours under protection; wash the filtrate with deionized water until the pH value of the washing water is 7, then wash twice with ethanol, and vacuum dry at 40°C for 24 hours to obtain Ni 2+ -Fe 2+ -Fe 3+ -CO 3 2- -LDHs layered precursors. The above samples were fired at 960°C for 5 hours to obtain spinel ferrite NiFe 2 O 4 .

[0035] Step B: Use a high-speed grinder to combine the obtained spinel ferrite NiFe 2 O 4 Grind into particles about 1-5μm; press N...

Embodiment 2

[0041] Keep other preparation conditions unchanged in Example 1. After step D is completed, press NiFe 2 O 4 The mass accounts for 25% of the final magnetic micro spherical alumina, weigh 2g NiFe 2 O 4 -SiO 2 -γ-Al 2 O 3 The microspheres were ultrasonically dispersed in 160ml of deionized water and then transferred to a stirred and heated reactor containing 1.93g of aluminum n-butoxide, hydrolyzed in a water bath at 85°C for 30 minutes, and concentrated HNO was added dropwise 3 When the pH value of the system reached 1, the temperature was raised to 95°C and refluxed and stirred for 24 hours. The resulting NiFe 2 O 4 -SiO 2 -γ-Al 2 O 3 The microsphere sol was dried at 70℃ for 24h to obtain NiFe 2 O 4 -SiO 2 -Al(OH) 3 Dry gel particles.

[0042] Put the product in the muffle furnace at 10℃·min -1 The temperature is increased to 600℃ and kept for 4h, and finally cooled to room temperature with the furnace to obtain magnetic micro spherical NiFe 2 O 4 -SiO 2 -γ-Al 2 O 3 . Determined ...

Embodiment 3

[0044] Step A: Weigh 3.49g Co(NO) in a molar ratio of 3:5:2 3 ) 2 ·6H 2 O, 3.98g FeCl 2 ·4H 2 O and 3.23gFe(NO 3 ) 3 ·9H 2 Dissolve O in 40ml and remove O 2 Prepared into a mixed salt solution in deionized water.

[0045] Others are the same as in Example 1. The magnetic microspherical CoFe is finally prepared 2 O 4 -SiO 2 -γ-Al 2 O 3 .

[0046] Determined CoFe 2 O 4 -SiO 2 -γ-Al 2 O 3 CoFe in microspheres 2 O 4 , SiO 2 And Al 2 O 3 The mass fractions are 27.6%, 30.2% and 42.2%, respectively. CoFe 2 O 4 -SiO 2 -γ-Al 2 O 3 The specific saturation magnetization is 24.46emu·g -1 , The coercivity is 1203Oe.

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Abstract

The invention provides a core-shell structure magnetic micro-spherical alumina MeFe2O4-SiO2-Al2O3 and the preparation method. According to the positioning effect of the LDHs laminated metal element, the invention firstly prepares the Me-Fe2+-Fe3+-LDHs laminated precursor by introducing the Me2+, Fe2+ and Fe3+ into the hydrotalcite laminate, and the spinel ferrite MeFe2O4 is formed by high-temperature roasting; the Na2SiO3.9H2O or silicon ester hydrolysis is adopted to coat a SiO2 protection layer on the surface of the MeFe2O4, the organic alcohol aluminum hydrolysis method is adopted to coat the alumina layer for a plurality of times, and finally the magnetic micro-spherical alumina MeFe2O4-SiO2-Al2O3 is obtained. The method saves the forming process of the traditional preparation method, and adjusts the magnetic structure and pore structure of the samples by changing the thickness of the SiO2 protection layer and the adding quantity of the magnetic object MeFe2O4 for meeting the application requirement of the magnetic stable bed process.

Description

[0001] Field [0002] The invention relates to a core-shell structure magnetic microspherical alumina and a preparation method thereof. The magnetic microspherical alumina can be used as a catalyst or a catalyst carrier in a magnetically stabilized bed process. Background technique [0003] Micro-spherical alumina has excellent pore structure, large specific surface area, good physical strength and acid and alkali resistance stability, and has been used more and more widely as a fluidized bed and suspended bed catalyst or catalyst carrier. However, the particles of micro-spherical alumina are small. Like other fine particle catalysts, the turbulence and forced stirring of the reaction materials are used to catalyze the reaction in fluidized bed and suspended bed processes, and there are poor mass transfer and It is difficult to separate and recover the catalyst after the reaction. [0004] In recent years, as a new form of reaction, the magnetically stabilized bed process has attra...

Claims

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Application Information

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IPC IPC(8): B01J23/755B01J23/75B01J32/00
Inventor 李殿卿林彦军李峰冯俊婷
Owner BEIJING UNIV OF CHEM TECH
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