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Nano-grade lanthanum titanium compound oxide, its preparation method and application

A titanium composite oxide, nano-scale technology, applied in the direction of metal/metal oxide/metal hydroxide catalysts, chemical instruments and methods, chemical/physical processes, etc., can solve the problem of large particle size range, agglomeration, and small specific surface area etc. to achieve the effect of reducing viscosity and preventing carbonization

Inactive Publication Date: 2006-02-01
CHONGQING UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The lanthanum-titanium composite oxide synthesized by the first two preparation methods above reduces the heterocrystalline phase by increasing the calcination temperature, which often easily leads to a larger particle size (micron order) and a smaller specific surface area (2 / g); and the particle size range of the lanthanum-titanium composite oxide synthesized by the third method is very large, and the synthesis method is inconvenient. When it is applied to the synthesis process of organic materials, the general dispersion performance is low, and phenomena such as agglomeration are prone to occur. To slow down the embedding of active centers and reduce the carbonization of the reaction system due to excessive viscosity under high temperature conditions

Method used

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  • Nano-grade lanthanum titanium compound oxide, its preparation method and application
  • Nano-grade lanthanum titanium compound oxide, its preparation method and application

Examples

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Effect test

Embodiment 1

[0010] Example 1 An organic precursor was prepared with raw materials at a molar ratio of lanthanum-titanium metal ion of 2:1. Disperse butyl titanate with anhydrous ethanol, wherein the molar ratio of metal titanium ion: anhydrous ethanol is 1:20, and adjust the pH to 1.0 with concentrated nitric acid to obtain a titanium sol. Dissolve lanthanum trioxide in nitric acid, add deionized water, the molar ratio of lanthanum trioxide: nitric acid: deionized water is 1:2:16, and the molar concentration of lanthanum nitrate is 0.5mol / dm 3 , Dissolve an appropriate amount of polyethylene glycol (with a molecular weight of 1000) in a lanthanum nitrate solution and stir at 40°C to form a colorless sol. Slowly drip the lanthanum sol into the titanium sol with vigorous stirring (rotational speed is 3000 rpm), rapidly stir and dehydrate under reduced pressure at 90°C for 3 hours to form a milky white sol, naturally cool to room temperature to form a milky white gel, and place the gel at 40°C A...

Embodiment 2

[0011] Example 2 An organic precursor was prepared with the raw materials at a molar ratio of lanthanum-titanium metal ion of 2:1. Disperse butyl titanate with anhydrous ethanol, wherein the molar ratio of metal titanium ion: anhydrous ethanol is 1:26, and adjust the pH to 1.5 with concentrated nitric acid to obtain a titanium sol. Dissolve lanthanum trioxide in nitric acid, add deionized water, the molar ratio of lanthanum trioxide: nitric acid: deionized water is 1:2:15, and the molar concentration of lanthanum nitrate is 0.6mol / dm 3 , Dissolve an appropriate amount of polyethylene glycol (with a molecular weight of 4000) in the lanthanum nitrate solution and stir at 30°C to form a colorless sol. Slowly drip the lanthanum sol into the titanium sol with vigorous stirring (rotating speed is 3500 rpm), rapidly stir and dehydrate under reduced pressure at 90°C for 4 hours to form a milky white sol, naturally cool to room temperature to form a milky white gel, and place the gel at 40...

Embodiment 3

[0012] Example 3 An organic precursor was prepared with the raw materials at a molar ratio of lanthanum-titanium metal ion of 2:1. Disperse butyl titanate with anhydrous ethanol, wherein the molar ratio of metal titanium ion: anhydrous ethanol is 1:30, and adjust the pH to 2.0 with concentrated nitric acid to obtain a titanium sol. Dissolve lanthanum trioxide in nitric acid, add deionized water, the molar ratio of lanthanum trioxide: nitric acid: deionized water is 1:2:14, and the molar concentration of lanthanum nitrate is 0.8mol / dm 3 , Dissolve an appropriate amount of polyethylene glycol (molecular weight: 20000) in the lanthanum nitrate solution and stir at 30°C to form a colorless sol. The lanthanum sol was slowly dropped into the titanium sol with vigorous stirring (speed of 4000 rpm), and the mixture was quickly stirred and dehydrated under reduced pressure at 90°C for 6 hours to form a milky white sol, which was naturally cooled to room temperature to form a milky white ge...

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Abstract

The composition of nano-grade lanthanum titanium compound oxide is La2-4Ti2-9O7-24, in which La:Ti:O (atom ratio)=2-4:2-9:7-24, LawTi2O7 and La4Ti9O24 are existed in micro-crystal state, its average grain size is 28nm-35nm, and its specific surface area is greater than 60 sq.m / g. Said compound oxide can be used as catalyst for preparing lactide by utilizing lactic acid dehydration and polycondensation, can improve viscosity of reaction system and can effectively reduce lactic acid oligomer cracking temp., and the yield of lactide is 80%-90%.

Description

Technical field [0001] The invention relates to a nano-level lanthanum-titanium composite oxide superfine powder and its synthesis process and application. technical background [0002] Binary lanthanum titanium oxide is generally prepared by the co-solvent method [see Mitsunori Yokoyama, Journal of Crystal Growth, North-Holland Amsterdanm, 1986 V96, P490~496 and Macchesney JB, J. Am. Ceram. Soc., 1962, 45(9 ): P416~422] Single crystal series, solid phase method [Michael Kestigian, Roland Ward, J. Am. Soc., 1995, 77(12): P6199~6200 and Xiang Yong et al., The Silicate Bulletin, 2001, V2 , P51~54] Preparation of La 2 O 3 -TiO 2 The series is mainly used as a ceramic dielectric material. Hydrothermal method [Matijevic, et al. United Staes Patent 5900223, May 4, 1999] to synthesize perovskite-type compound crystal powder. Lanthanum titanium has a unique electronic structure (La4f 0 5d 1 6s 2 , Ti 3d 2 4s 2 There are many empty orbitals in ), which can provide goo...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01J23/10B01J37/03C04B35/46C04B35/624
Inventor 王远亮谷俐王建华潘君
Owner CHONGQING UNIV