A kind of co-precursor method normal pressure drying method for preparing bulk silica airgel

Abstract

The invention discloses a method for preparing blocky silicon dioxide aerogel through ambient pressure drying by means of a co-precursor method. The preparation method includes the steps that two silicon sources A and B are selected, and an organic solvent and deionized water are added into the silicon source A and the silicon source B respectively to obtain a silicon source solution A and a silicon source solution B; acidic catalysts are added into the silicon source solution A and the silicon source solution B respectively for hydrolysis to obtain a silicon source precursor hydrolysis solution A and a silicon source precursor hydrolysis solution B; under the stirring state, the silicon source precursor hydrolysis solution B is added into the silicon source precursor hydrolysis solution A, and an alkaline catalyst is added for polycondensation to obtain wet gel, wherein the concentration of the alkaline catalyst is 0.8-1.3 mol / L; solvent exchange is conducted after the wet gel is aged, and solvent exchanged wet gel is obtained; the solvent exchanged wet gel is subjected to normal-pressure graded drying. The technical process related to the method is simple, the extra surface modification step is not needed, and the preparation period is short. A prepared sample is good in blocking property, has certain mechanical strength and can meet requirements of more special fields.

Description

technical field [0001] The invention relates to the technical field of bulk airgel preparation, in particular to a method for preparing bulk silica airgel by co-precursor drying under normal pressure. Background technique [0002] Silicon dioxide (SiO 2 ) Airgel is a new type of nanoporous material with low density, low electrical and thermal conductivity, low dielectric coefficient, low refractive index, high specific surface area, and high porosity, and its nanoporous framework only accounts for 10% of the whole Around, up to 90% air fills its skeletal pores. These unique properties make SiO 2 Aerogels are widely used in ultra-low density thermal insulation materials, high-efficiency high-energy electrodes, acoustic impedance coupling materials, gas adsorption and membrane separation, high-efficiency catalysts and their supports, etc. In the preparation of silica aerogels, tetraethyl orthosilicate is currently the most widely used silicon source. However, the airgel obt...

AI Technical Summary

Problems solved by technology

In the preparation of silica aerogels, tetraethyl orthosilicate is currently the most widely used silicon source. However, the airgel obtained by using tetraethyl orthosilicate alone as a silicon source tends to have a weak network skeleton, low strength, Poor agglomeration, which greatly limits the application and promotion of airgel

[0003] In this regard, researchers such as Hu Yin used methyltrimethoxysilane, absolute ethanol and deionized water as raw materials to prepare SiO with certain flexibility by using an acid-base two-step catalytic method. 2 Aerogel, but the hydrophobicity of the prepared sample is poor, and the drying process adopts low-temperature drying for as long as 5-6 days, and the long preparation cycle is not conducive to industrial production

In order to improve the mechanical strength of airgel for better practical application, researchers at home and abroad have done a lot of research and improvement in the synthesis of airgel and related products in recent years, mainly focusing on the introduction of reinforcing phases to prepare airgel composites. materials to improve the mechanical properties of aerogels, but there is little research on the synthesis of silica aerogels with certain mechanical strength and bulk

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