Method for preparing SiO2 aerogel with nanometer apertures under normal pressure

Abstract

The normal pressure process of preparing SiO2 aerogel with nanometer pores belongs to the field of inorganic non-metal material preparation. The present invention features the cheap water glass as silicon source, the surfactant to alter the surface property of SiO2 aerogel hydrophobicity, the ion exchange resin to eliminate great amount of sodium ions and to lower the effect of the sodium ions on the heat conductivity of SiO2 aerogel, and template agent to control narrow pore size distribution and pore size for realize nanometer level super heat insulating material structure. The normal pressure process has greatly reduced preparation time, and the produced SiO2 aerogel has both hydrophobicity and heat stability and performance similar to SiO2 aerogel produced through supercritical process.

Description

technical field [0001] The invention belongs to the field of inorganic non-metallic materials, in particular to a method for preparing nanoporous SiO at normal pressure 2 Airgel method. Background technique [0002] SiO 2 Aerogels are nanoporous materials with many potential applications. In terms of heat insulation, due to SiO 2 The airgel scale is a porous material smaller than 50 nanometers, and the diameter of the pores is smaller than the mean free path of the molecule, making SiO 2 When airgel is used as a thermal insulation material, the gas molecules do not collide or the probability is very small, the heat conduction of the gas is greatly reduced, and the thermal conductivity is lower than that of air. The thermal conductivity at room temperature is 0.03-0.05W / mK . SiO 2 Airgel is 90% to 98% gas, with a density of 0.05 to 0.2g / cm 3 , high specific surface area, so that it will have a wide range of applications in adsorbents and catalyst supports. SiO 2 The ...

AI Technical Summary

Problems solved by technology

However, according to data records, when tetraethyl orthosilicate is used as the silicon source, the raw materials are not easy to obtain and the price is expensive.

When water glass is used as the silicon source, most of the sodium ions remain, which affects the reduction of the thermal conductivity of the product

The supercritical drying method used requires large investment and high cost, and the operation of high-pressure equipment is dangerous

However, the normal pressure drying method used has a long cycle time and is hydrophilic, so it cannot reach the supercritical drying method to prepare SiO 2 The properties of airgel

Simultaneously produced SiO 2 The large pore size distribution of airgel cannot fully guarantee the SiO 2 All or most of the airgel pores become nano-scale pores, so the thermal insulation performance of the material cannot meet the ideal performance requirements of super thermal insulation materials

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