Method for preparing modified silicon dioxide aerogel material through normal-pressure drying and by external circulation mode

Abstract

The invention provides a preparation method of a modified silicon dioxide aerogel material. The preparation method comprises the following steps: placing an aged silicon dioxide wet gel and a modifierprecursor into a reaction container, performing external circulation hydrolysis on the modifier precursor, and returning to a reaction container and performing modified reaction to obtain the modified silicon dioxide aerogel material, wherein the modifier can encounter water to generate polymerization reaction to generate the modifier precursor. The traditional organic solvent exchange process link is abandoned, an external circulation one-step modification mode is adopted, the consumption quantity of the organic solvent is small, the cost is low, the environmental hazard is small, use and waste of the organic solvent in the link are avoided, a large amount of silane modifiers are saved for the subsequent surface modification process, the surface modification efficiency is improved, the cost is reduced and the environmental hazard is avoided; furthermore, the preparation method is short in preparation cycle, high in efficiency, simple and convenient to operate, mild in reaction condition and suitable for industrialized continuous production.

Description

technical field [0001] The invention relates to the technical field of high-performance porous materials, and relates to a preparation method of a modified silica airgel material. In particular, it relates to a method for preparing a modified silica airgel material by drying under normal pressure in an external circulation mode. Background technique [0002] Airgel, also known as xerogel, is a solid material form, a highly dispersed solid material that is composed of colloidal particles or polymer molecules aggregated into a nanoporous network structure, and filled with a gaseous dispersion medium in the pores , and one of the least dense solids among existing materials, aerogels have continuous mesoporous pores, which are nanostructures composed of interconnected nanoparticles or polymer chains with a characteristic diameter of about 10 nm. These nanostructures endow them with high surface area, relatively large pore volume, low packing density, and low thermal and acousti...

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Problems solved by technology

However, the preparation period of this method is long, and the cost of the precursor tetraethyl orthosilicate used is relatively high, which is not conducive to large-scale industrial production

Trimethylchlorosilane itself is relatively active, and it can be hydrolyzed to generate corrosive hydrochloric acid gas when it meets water, which poses a serious threat to the environment and operators.

However, if organic solvents such as alcohols are used as solvents for exchanging pore water, the consumption of silane modifiers is still greater than the amount required for actual modification, resulting in the loss of silane surface modifiers, and correspondingly, the cost will be greatly increased. , limiting the popularization and use of airgel products

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