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Method for rapidly preparing hydrophobicsilica aerogel by carbon dioxidesubcritical drying method

A carbon dioxide and water silicon oxide technology, applied in the direction of silicon dioxide, silicon oxide, etc., can solve the problems of hidden safety hazards, high energy consumption, long preparation time, etc., to reduce energy consumption, save energy, and save surface modification process. Effect

Inactive Publication Date: 2015-09-16
田雷
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the critical temperature and pressure of methanol are 240°C and 7.95MPa respectively. To make the whole system fully reach the supercritical state of methanol, the heating source will be close to 300°C, and the pressure will be close to 20MPa, which will cause the following problems: 1) high cost energy consumption; 2) huge potential safety hazard; 3) long preparation time

Method used

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  • Method for rapidly preparing hydrophobicsilica aerogel by carbon dioxidesubcritical drying method
  • Method for rapidly preparing hydrophobicsilica aerogel by carbon dioxidesubcritical drying method
  • Method for rapidly preparing hydrophobicsilica aerogel by carbon dioxidesubcritical drying method

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Embodiment 1

[0033] Sol-gel preparation: extract 1000 grams of methanol with a content of 99.5%, 65 grams of deionized water, mix and stir and drop into 1% concentration of hydrochloric acid aqueous solution, after stirring evenly, drop into orthosilicate methyl ester (99%wt) 100 grams at a uniform speed gram and 25 grams of methyltriethoxysilane, and stirred at a constant speed for about 10-60 minutes, so that the pH value reached about 2. Add 2% aqueous sodium hydroxide solution dropwise to increase the pH value to 8, stir evenly, and form a gel after standing for 10-60 minutes. Subcritical drying can be performed after aging the gel at 60°C for 10 hours.

[0034]According to the critical parameters of carbon dioxide in Table 1, adjust the carbon dioxide to a subcritical state.

[0035] Table 1: Carbon dioxide critical state parameters

[0036]

[0037] Subcritical drying: put the aged gel in an autoclave, immerse and close the autoclave with industrial methanol, slowly inject carbo...

Embodiment 2

[0053] Sol-gel preparation: extract 1000 grams of dehydrated ethanol, dissolve it with 65 grams of deionized water, drop into 10% concentration of acetic acid aqueous solution, stir to form ethanol acidic dosing, get tetraethyl orthosilicate (99%wt ) and 50 grams of methyltriethoxysilane, add the ethanol acidic solution prepared in the previous step at a uniform speed until the pH value reaches about 2, and stir at a constant speed for about 10-60 minutes. Drop 1% ammonia solution to increase the pH value to 7.4, stir evenly to prepare silica sol, inject the silica sol into glass fiber blankets with length, width and thickness: 20cm, 20cm and 1cm, and let it stand for about 10-60 Minutes later, the gel glass fiber composite blanket is made. Place the gel glass fiber composite blanket in an aging kettle at 70°C for 5 hours.

[0054] Subcritical drying: Place the aged gel glass fiber blanket in an autoclave and immerse it in methanol and close it, slowly inject carbon dioxide a...

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Abstract

The invention discloses a method for rapidly preparing hydrophobicsilica aerogel by a carbon dioxidesubcritical drying method. The method disclosed by the invention comprises the following steps: (1) adding alcohol to a mixed solution of silicate ester, ethoxysilane and water and fully hydrolyzing in the presence of acid to obtain sol; (2) adding alkali into the sol, adjusting the pH value of the system to 6-10 to obtain sol which is nearly neutral or alkaline; mixing the sol which is nearly neutral or alkaline with fibers to prepare a gel-fiber composite material; and aging the obtained wet gel or aerogel-fiber composite material; and (3) putting the aged wet gel or aerogel-fiber composite material in a drying kettle and drying at a carbon dioxidesubcritical state to obtain the finished product. According to the method disclosed by the invention, a surface hydrophobic modification link is omitted, the obtained gel substrate is elastic and high in porosity; in addition, the method is performed at a temperature of 10-30 DEG C under a pressure lower than 6MPa, thereby greatly reducing energy consumption.

Description

technical field [0001] The invention relates to the technical field of airgel production, in particular to a method for rapidly preparing hydrophobic silica airgel by using a carbon dioxide subcritical drying method. The invention also relates to airgel and airgel fiber composites produced by this method. Background technique [0002] Airgel is known as one of the top ten new materials with the most potential in the future. Because its porosity can be as high as 95%, and its thermal conductivity and density are as low as 0.01W / m. It has unparalleled advantages in noise reduction and sound insulation, and will definitely contribute to my country's energy conservation and emission reduction in the future. [0003] Airgel was invented by Professor Kistler of Stanford University in 1931, using water glass as a silicon source and preparing aerogel by sol-gel process, but the process is complicated and has not been applied. [0004] By the 1960s, Nicolaon et al. used silicon alko...

Claims

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Application Information

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IPC IPC(8): C01B33/16C04B30/02
Inventor 田雷董海兵
Owner 田雷
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