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Silicon dioxide aerogel with high specific surface area and fast preparation method thereof

A high specific surface area, silicon dioxide technology, applied in the direction of silicon dioxide, silicon oxide, chemical instruments and methods, etc., can solve the restrictions on the popularization and use of silicon dioxide airgel, high cost of silicon dioxide airgel, nanometer Problems such as hole collapse and cracking, to achieve fast hydrolysis rate, reduce volatilization, and less solvent volatilization loss

Active Publication Date: 2017-05-17
GUANGDONG ALISON HI TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, currently restricted by production efficiency and process conditions, the cost of silica airgel is relatively high, and the product quality is unstable, especially in the process of production, because the solvent used in silica airgel is volatile organic Solvents are prone to volatilization during preparation, gelation, aging, drying, etc., resulting in the collapse and rupture of the formed nanopores under the capillary force caused by surface tension, and the colloidal structure is destroyed. Silica airgel material yield is low, the specific surface area is low, and the cost is high, which greatly restricts the promotion and use of silica airgel in the market

Method used

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  • Silicon dioxide aerogel with high specific surface area and fast preparation method thereof

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Embodiment 1

[0027] The method for rapidly preparing high specific surface area silica airgel of the present embodiment comprises the following steps:

[0028] (1) Cool ethyl orthosilicate, absolute ethanol, oxalic acid, ammonia, water, and n-hexane to 5°C;

[0029] (2) Mix ethyl orthosilicate, absolute ethanol, oxalic acid, and water in a constant temperature reactor at 5°C, then add ammonia water and n-hexane to mix, then let the gel stand, record the gel time, and age at 5°C for 8 hours ; The molar ratio of tetraethyl orthosilicate, absolute ethanol, oxalic acid, water, ammonia water and n-hexane is 1:18:0.005:4:0.005:0.2;

[0030] (3) Transfer the aged gel into ethylene glycol dimethyl ether, and change the liquid at 25° C. for 2 hours;

[0031] (4) Perform supercritical drying on the gel after solvent exchange, and dry it with supercritical carbon dioxide at 70° C. and 19 MPa for 6 hours to obtain silica airgel, and measure its specific surface area.

Embodiment 2

[0033] The method for rapidly preparing high specific surface area silica airgel of the present embodiment comprises the following steps:

[0034] (1) Cool ethyl orthosilicate, absolute ethanol, oxalic acid, ammonia, water, and n-hexane to 5°C;

[0035] (2) Mix ethyl orthosilicate, absolute ethanol, oxalic acid, and water in a constant temperature reactor at 5°C, then add ammonia water and n-hexane to mix, then let the gel stand, record the gel time, and age at 5°C for 8 hours ; The molar ratio of tetraethyl orthosilicate, absolute ethanol, oxalic acid, water, ammonia water and n-hexane is 1:18:0.005:4:0.005:0.5;

[0036] (3) Transfer the aged gel into ethylene glycol dimethyl ether, and change the liquid at 25° C. for 2 hours;

[0037] (4) Perform supercritical drying on the gel after solvent exchange, and dry it with supercritical carbon dioxide at 70° C. and 19 MPa for 6 hours to obtain silica airgel, and measure its specific surface area.

Embodiment 3

[0039] The method for rapidly preparing high specific surface area silica airgel of the present embodiment comprises the following steps:

[0040] (1) Cool tetraethyl orthosilicate, methanol, nitric acid, ammonium carbonate buffer, water, and n-hexane to 1°C;

[0041] (2) Mix ethyl orthosilicate, methanol, nitric acid, and water in a constant temperature reactor at 1°C, then add ammonium carbonate buffer and n-hexane to mix, then let the gel stand, record the gel time, and age at 1°C 8h; the molar ratio of ethyl orthosilicate, absolute ethanol, nitric acid, water, ammonium carbonate buffer and n-hexane is 1:20:0.01:2:0.01:0.3;

[0042] (3) Transfer the aged gel into ethylene glycol dimethyl ether, and change the liquid at 15° C. for 3 hours;

[0043] (4) Perform supercritical drying on the gel after solvent exchange, and dry it with supercritical carbon dioxide at 70° C. and 19 MPa for 6 hours to obtain silica airgel, and measure its specific surface area.

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Abstract

The invention discloses a silicon dioxide aerogel with a high specific surface area and a fast preparation method thereof. The preparation method comprises the following steps: cooling all raw materials, in a cooling condition, mixing a silicone precursor, a solvent, an acidic catalyst and water, then adding an alkaline catalyst and a reaction accelerant, leaving the mixture to stand to gelatinize the mixture, and aging the mixture in the condition; transferring the aged gel into an exchange liquid to be soaked for solvent exchange; and performing supercritical drying on the gel after solvent exchange to obtain the silicon dioxide aerogel. By adopting a mode of cooling preparation, collapse of holes of the aerogel in a nano-structure due to solvent evaporation in the preparation and gel aging processes is avoided, and meanwhile, by using the reaction accelerant, the reaction rate at a low temperature is accelerated and the preparation efficiency is improved. In addition, an exchange liquid is used to replace the solvent in the surface layer of the gel before supercritical drying, so that the damage of the aerogel structure due to solvent evaporation in the temperature-raising and pressure-raising process is reduced, and the prepared silicon dioxide aerogel has a good specific surface area.

Description

technical field [0001] The invention belongs to the technical field of inorganic nanoporous materials, in particular to a silica airgel with a high specific surface area and a rapid preparation method thereof. Background technique [0002] Silica airgel is a new type of nanoporous inorganic material with a continuous three-dimensional structure. Silica has great porosity (85%-99%), very high specific surface area (700-1000㎡ / g), so it can play an important role in many fields, such as in the field of catalysis as a catalyst carrier, Participate in various reactions; in the field of medicine, as a drug carrier, play a targeting role; in the field of environment, as an adsorbent, effectively adsorb various organic pollutants. [0003] However, currently restricted by production efficiency and process conditions, the cost of silica airgel is relatively high, and the product quality is unstable, especially in the process of production, because the solvent used in silica airgel i...

Claims

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Application Information

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IPC IPC(8): C01B33/16
CPCC01B33/163C01P2006/12
Inventor 张秋华卫荣辉陈文军周婉玲袁兵郑亚莉但梁丰
Owner GUANGDONG ALISON HI TECH
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