Method for quick-speed preparing aerogel by hydro-thermal synthesis at low cost

A hydrothermal synthesis and aerogel technology, applied in the direction of silica, alkali metal silicate, silicate, etc., can solve the problems of insufficient specific surface area, insufficient porosity, small pore size, etc., and reach the surface Tension and capillary force reduction, integrity maintenance, accelerated aging effects

Inactive Publication Date: 2009-06-17
纳诺科技有限公司 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The mesoporous or porous materials prepared by hydrothermal synthesis have certain particularities, but due to the limitations of the structure itself, such as insufficient porosity, insufficient specific surface area, too small pore size, and too high density, many properties of the material are still limited. It cannot reach the level of airgel, especially the thermal conductivity, adsorption performance, etc. Therefore, the prepared mesoporous materials are generally only used in the field of molecular sieve adsorption and filtration, and the application range is narrow

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035] Alkaline silica sol is used as reactant, tetraalkyl ammonium chloride is used as structure directing agent, after mixing according to the volume ratio of 1:100, the pH value is adjusted to 10.0 with oxalic acid, the reaction kettle is sealed, the temperature is raised to 150°C, and the temperature is maintained It was left to stand for 1 hour, and then the temperature was raised to 200° C., and the reaction was continued for 3 hours. After cooling, open the reaction kettle, take out the gel formed in the kettle, and dry it in an infrared oven at 80°C for 3 hours to obtain a silica airgel with a complete skeleton structure, with a compressive strength of 0.5Mpa and a thermal conductivity of 0.018w / (m·K), the average pore diameter is 40nm.

Embodiment 2

[0037] Water glass diluted with water is used as the reactant, the volume ratio of water glass and water is 1:5, and citric acid is used as the structure directing agent, which is added into the hydrothermal reaction kettle according to the volume ratio of 1:12, and after mixing evenly, Adjust the pH value to 9.0 with HCl, seal the reaction vessel, heat to 180°C, keep the temperature unchanged for 2 hours, then raise the temperature to 250°C, and continue the reaction for 5 hours. After cooling, open the hydrothermal reaction kettle, take out the gel formed in the kettle, and dry it in a convection circulation oven at 100°C for 2.5 hours to obtain a silica aerogel with a complete skeleton structure and a compressive strength of 2.3Mpa. The thermal conductivity is 0.017w / (m·K), and the average pore size is 20nm.

Embodiment 3

[0039] Acidic aluminum sol was used as the reactant, tetrapropylammonium hydroxide (TPAOH) was used as the structure-directing agent, mixed according to the volume ratio of 1:0.08, then added to the hydrothermal reaction kettle, and KHCO 3 Adjust the pH value of the aqueous solution to 4.5, seal the reaction vessel, heat to 150°C, and keep the temperature unchanged for 0.5 hours. After cooling, open the hydrothermal reaction kettle, take out the gel generated in the kettle, and dry it in a microwave oven for 0.5 hours to obtain an alumina airgel with a complete skeleton structure, with a compressive strength of 1.8Mpa and a thermal conductivity of 0.015w / (m·K), the average pore diameter is 15nm. The obtained alumina airgel is heat-treated at 400°C for 2 hours to obtain an alumina airgel with a porosity of 92%, and a compressive strength of up to 3.8Mpa.

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PUM

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Abstract

The invention discloses a method for preparing aerogel materials by combining hydrothermal synthesis technology and sol-gel technology. The prepared aerogel comprises one or more of alumina aerogel, silica aerogel, zirconia aerogel and titania aerogel. The method comprises the following steps: mixing a reactant and a structure-directing agent according to certain proportion, and adding a pH value control agent to adjust the pH value; sealing hydrothermal reaction equipment, heating the mixture to be between 50 and 280 DEG C, making the mixture stand for 0 to 72 hours, raising the temperature to be between 60 and 300 DEG C, and continuously reacting for 0.1 to 72 hours; and cooling gel, taking out the gel, drying the gel and obtaining the aerogel. Compared with the prior art, the method has low reaction temperature and pressure, small equipment investment and simple and controllable technology, reduces potential safety hazards, greatly improves the preparation speed of the aerogel, saves the production cost, and is favorable to realize commercial mass production.

Description

technical field [0001] The invention relates to a method for preparing airgel, in particular to a method for preparing airgel by a hydrothermal synthesis method, and belongs to the field of chemical material preparation. Background technique [0002] Airgel is a new type of low-density, high-porosity nanoporous material with controllable structure. It has a continuous network structure, nanoscale pore size and particle diameter. The material with the best thermal insulation performance so far. Because of its nanoporous structure (1-100nm), low density (1-500kg / m 3 ), low dielectric constant (1.1-2.5), low thermal conductivity (0.003-0.025w / m k), high porosity (80%-99.8%), high specific surface area (200-1000m 2 / g) and other characteristics, airgel is obviously different from its corresponding macroscopic glassy material, and has unique properties in mechanics, acoustics, heat, optics, etc., such as extremely low solid and gaseous thermal conductivity, low refractive index...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/02C01B33/14C01B33/32
Inventor 张蓉艳金承黎张洪彪余盛锦肖愉
Owner 纳诺科技有限公司
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