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Method for preparing silicon dioxide aerogel with low density and large specific surface area at ordinary pressure

A large specific surface area, silica technology, applied in the direction of silica, silica, etc., can solve the problems of large modifier dose, high airgel density, and high cost

Inactive Publication Date: 2014-05-28
HEFEI KESIFU SAFETY TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Chinese patents CN201210121968.0 and CN201210114691.9 use sodium silicate as a raw material and are prepared by a two-step sol-gel method. After ion exchange, they are aged with tetraethyl orthosilicate in ethanol solution, and finally undergo solvent exchange and modification. Airgel is obtained by pressing and drying, and aging is carried out with tetraethyl orthosilicate, the cost is too high, and the density of the obtained airgel is also too high
Ni Wen et al. used water glass as the silicon source, and used solvent exchange and surface modification to prepare silica airgel with a specific surface area of ​​643m2 / g. A significant disadvantage of the one-step method is the large amount of modifier consumed. ; n(TMCS):n(H2O)=0.2-0.4, people such as Sung-Woo Hwang adopt one-step method to prepare airgel with water glass as silicon source, n(TMCS):n(SiO2)=0.93-32.49

Method used

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  • Method for preparing silicon dioxide aerogel with low density and large specific surface area at ordinary pressure
  • Method for preparing silicon dioxide aerogel with low density and large specific surface area at ordinary pressure
  • Method for preparing silicon dioxide aerogel with low density and large specific surface area at ordinary pressure

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] (1) Mix 5ml of 34% industrial water glass with a modulus of 3.3 and 15ml of deionized water in a beaker, and stir for 5 minutes;

[0029] (2) Pass through the 732 strong acidic ion exchange resin. Before passing through the column, pass through the column with 80°C deionized water to fully expand the resin particles, and then pass the water glass solution heated to 45°C through the column to obtain a pH of 3. Silica sol, stir on a stirrer at room temperature, add 0.5mol / L ammonia solution to adjust the pH of the solution to 5~6, then add 0.5ml N,N dimethylformamide, stir for 2min, after about 15min it will completely gel, In a sealed container, heat in a water bath at 50°C for 12 hours;

[0030] (3) Cut the gel into pieces, add ethanol to the gel for solvent exchange, and perform solvent exchange in a water bath at 50°C, each exchange for 8 hours, a total of 3 times. The exchanged solution is recovered and can be recycled;

[0031] (4) Exchange ethanol with n-hexane, ...

Embodiment 2

[0035] (1) Mix 5ml of industrial water glass with a modulus of 3.5 and a mass concentration of 32% and 15ml of deionized water in a beaker, and stir for 5 minutes;

[0036] (2) Pass through the 732 strong acidic ion exchange resin. Before passing through the column, pass through the column with 80°C deionized water to fully expand the resin particles, and then pass the water glass solution heated to 45°C through the column to obtain a pH of 3. Silica sol, stir on a stirrer at room temperature, add 0.5mol / L ammonia solution, adjust the pH of the solution to 5~6, add 1ml of glycerol, stir for 2min, and gel completely after about 2h, seal the container, and put it in a water bath at 50°C Heating for 12 hours;

[0037] (3) Cut the gel into pieces, add acetone to the gel for solvent exchange, and perform solvent exchange in a water bath at 50°C, each exchange for 8 hours, a total of 3 times. The exchanged solution is recovered and can be recycled;

[0038](4) Exchange acetone wit...

Embodiment 3

[0042] (1) Mix 5ml of industrial water glass with a modulus of 3.5 and a mass concentration of 32% and 15ml of deionized water in a beaker, and stir for 5 minutes;

[0043] (2) Pass 732 strong acidic ion exchange resin. Before passing through the column, pass through the column with 80°C deionized water to fully expand the resin particles. Then pass the water glass solution at room temperature through the column to obtain a silica sol with a pH of 3. Stir on a stirrer at room temperature, add 0.5mol / L ammonia solution during the period, adjust the pH of the solution to 6-7, then add 1.5ml of N,N dimethylformamide, stir for 2min, after about 2h it will completely gel, seal the container, Heating in a water bath at 50°C for 12 hours;

[0044] (3) Cut the gel into pieces, add acetone to the gel for solvent exchange, and perform solvent exchange in a water bath at 50°C, each exchange for 8 hours, a total of 3 times. The exchanged solution is recovered and can be recycled;

[004...

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Abstract

The invention discloses a method for preparing silicon dioxide aerogel with low density and large specific surface area at ordinary pressure. The method comprises the steps of taking cheap industrial water glass as a precursor and absolute ethyl alcohol as a solvent, performing hydrolysis and polycondensation reaction by the catalysis of acid and alkali respectively to form wet gel, performing water bath drying and aging, performing solvent exchange for many times, and performing graded drying at the ordinary pressure after surface modification to form the silicon dioxide aerogel with the low density. According to the method, the completely modified super hydrophobic silicon dioxide aerogel is obtained by using the least amount of modifier; the cheap industrial water glass is adopted as a silicon source, so that the production cost is greatly lowered; and the energy source is greatly saved for drying at the ordinary pressure in comparison with supercritical drying.

Description

technical field [0001] The invention relates to a method for preparing silica airgel with low density and large specific surface area under normal pressure. The preparation method of silica airgel has low cost and high quality of prepared materials. It can be used in aerospace, energy, construction, anti-riot, It is widely used in sound insulation, catalyst and many other fields. Background technique [0002] Silica airgel is a lightweight nanoporous material with controllable structure, which has many excellent properties, such as high porosity, high specific surface area, low density, low thermal conductivity, etc. The preparation of silica airgel at home and abroad usually uses methyl orthosilicate, ethyl orthosilicate or "water glass" as raw materials, adopts sol-gel method, and is obtained by supercritical drying. Chen Guo, Zhang Jun, etc. (Chinese Patent, Application No. 201210078237.2) disclosed a method for preparing silica airgel by using tetraethyl orthosilicate a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/16
Inventor 何松程旭东毕海江李治杨晖陆松
Owner HEFEI KESIFU SAFETY TECH
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