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Method for preparing Nano silicon dioxide

A technology of nano-silica and silicic acid sol, applied in the directions of silica, silica, chemical instruments and methods, etc., can solve the problems such as difficult agglomeration of nanoparticles, difficult control of particle size, and easy occurrence of agglomeration.

Inactive Publication Date: 2005-06-15
BEIJING UNIV OF CHEM TECH +1
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Problems solved by technology

[0004] In order to solve the problem that the particle size is not easy to control and easy to agglomerate in post-treatment when preparing nano-silica by alkali metal silicate and acid precipitation reaction, the present invention proposes a method for preparing nano-silica, which can be used in alkali metal silicon dioxide A molecular network is formed in the salt solution precipitation reaction system to isolate the silicic acid sol colloid core, thereby controlling and preventing the colloid core growth, and the post-treatment process of the sol is simple, making the nanoparticles fluffy and difficult to agglomerate, suitable for industrial production

Method used

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Experimental program
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Effect test

Embodiment approach

[0024] 1. Extraction with low-carbon alcohol: the gel obtained in step B) is replaced with an appropriate amount of absolute ethanol for several times to solvent-replace the silicate ethanol gel, and then added to absolute ethanol to form silica alcohol gel Put the glue into the high-pressure reactor, under the supercritical conditions of 260°C-300°C, 7.0-9.5MPa, use absolute ethanol as the extraction solvent, and release the fluid after stabilizing for 0.5-1.0h to obtain a large specific surface area. It is a uniform nano-silica powder with a narrow particle distribution range and well-developed pores.

[0025] In addition to absolute ethanol, suitable solvents for extraction in the supercritical extraction process can also be low-carbon alcohols such as methanol and isopropanol. Its dosage is not strictly required, and is generally determined according to the economy of the synthesis reaction. The content of the extraction solvent can be controlled within the range of 20%-80...

Embodiment 1

[0028] Weigh Na 2 O and SiO 2 The percentage content is respectively 8.2% and 26% water glass solution 107.33g, joins the deionized water of 568ml, is made into Na 2 O concentration is the dilute water glass solution of 0.25mol / l, weigh polyethylene glycol-10000 5.2g and join in the above-mentioned water glass solution, stir to dissolve completely; Press Na 2 O / HAc=1.0:6.0 (molar ratio), weigh 51.16g of acetic acid and add water to be mixed with 1.0mol / L acetic acid solution for use; under constant stirring, the mixed solution of water glass and polyethylene glycol-10000 is heated up to 80 ℃, add the prepared 1.0mol / L acetic acid solution dropwise, after 2.5h, the dropwise addition is completed, continue to stir the white transparent suspension, age for 1 hour, stop heating and cool down to room temperature naturally, filter, wash with deionized water until neutral and dry Detection without Ac -1 After ionization, it was fully replaced with absolute ethanol three times, fil...

Embodiment 2

[0030] Weigh Na 2 O and SiO 2 The percentage content is respectively 100kg of concentrated water glass solutions of 7.06% and 22.58%, add 455.45kg of deionized water and dilute to Na 2 O concentration is the dilute water glass solution of 0.25mol / L, weighs polyethylene glycol-2000 4.5kg and joins in the above-mentioned water glass solution, stirs to dissolve completely; Press Na 2 O / HAc=1.0:5.0 (molar ratio), take 98% acetic acid 34.86kg and add deionized water 142.34kg to be made into 4.0mol / L acetic acid solution; Under constant stirring, 4.0mol / L acetic acid solution is heated up to 75 ℃, add dropwise the mixed solution of water glass and polyethylene glycol-2000, after 2.5h the dropwise addition is completed, continue to stir the white transparent suspension, age for 1 hour, stop heating and naturally cool down to room temperature, the pH value is 4.59, filter, Wash with deionized water to neutral and detect no Ac -1 After ionization, fully replace it with absolute etha...

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Abstract

A process for preparing nano-SiO2 includes such steps as adding water-soluble polymer and / or water-soluble organic C1-C8 alcohol to the solution alkali-metal silicate, stirring adding weak organic acid as catalyst, hydrolyzing reaction to obtain the hydrosol, washing, filter, and natural drying or supercritical extracting. The obtained amorphous nano-SiO2 has high purity and dispersity and large specific surface area.

Description

technical field [0001] The invention relates to a method for preparing nano silicon dioxide, in particular to a method for preparing nano silicon dioxide from alkali metal silicate. Background technique [0002] The synthesis methods commonly used in the preparation of nano-silica include precipitation method and sol-gel method (Sol-Gel method). The sol-gel method uses organic alcohol silicate as raw material, which is expensive, and its production cost is very high, so it is difficult to realize large-scale industrial production. Carry out synthesis with precipitation method, can adopt cheap alkali metal silicate (water glass) as raw material, but generally all adopt strongly acidic inorganic acid and alkali metal silicate to carry out precipitation reaction, as: Chinese patent 94117058 discloses a kind of " The method of "precipitating silicon dioxide" is to use alkali metal silicate and inorganic acid for precipitation reaction, and obtain silicon dioxide particles with ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/14C01B33/142C01B33/146C01B33/16
Inventor 杨儒李敏张广延刘埃林孔建民汪英杰周立平钟后国沈军
Owner BEIJING UNIV OF CHEM TECH
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