A kind of preparation method of massive aluminum oxide airgel

Abstract

The invention discloses a preparation method of a bulk alumina aerogel. The method includes the steps of: (1) adding a first alcohol solvent, a chelating agent, water and aluminum alkoxide into a reflux reaction device in order according to a mole ratio of 5-20:0.02-0.15:0.2-0.8:1, conducting stirring at 50-80DEG C for 5-60min to form a clear and transparent liquid, and then performing cooling to room temperature so as to obtain partially hydrolyzed aluminum sol; (2) mixing an acid catalyst, a second alcohol solvent and water evenly at room temperature, wherein the acid catalyst, the second alcohol solvent and water used in the step and the aluminum alkoxide involved in step (1) are in a mole ratio of 1:0.05-0.2:10-30:1.2-2.5; (3) adding the material of step (2) into the partially hydrolyzed aluminum sol of step (1), stirring the materials evenly, and then conducting standing to obtain transparent alumina gel; and (4) subjecting the alumina gel to airtight standing aging, and then carrying out supercritical fluid drying. The preparation method provided by the invention solves the difficulty of effective control of aluminum alkoxide hydrolysis by a two-step hydrolysis technique.

Description

technical field [0001] The invention belongs to the technical field of airgel preparation, and in particular relates to a method for preparing block alumina airgel. Background technique [0002] Airgel is a condensed material composed of nanoparticles or polymer molecules and filled with a gaseous medium inside. Due to its nanoporous network structure and its mesopore size less than 50nm, the flow of internal gas molecules is limited. Movement, causing it to effectively limit solid-phase heat transfer, gas-phase heat transfer and heat convection, so airgel has become the material with the lowest thermal conductivity among all solid and porous materials. Has great potential. At present, among the airgel insulation materials reported at home and abroad, SiO 2 Airgel materials are the most widely studied, and have been successfully used as thermal insulation materials in space stations, Mars probes, and vehicle water-cooled radiators. But SiO 2 Aerogels tend to sinter when ...

AI Technical Summary

Problems solved by technology

[0003] At present, the preparation of alumina airgel is usually prepared by sol-gel method using inorganic aluminum source or aluminum alkoxide as the precursor. It is very difficult to prepare bulk alumina with aluminum alkoxide as the precursor. The reason is that the aluminum alcohol source It is very sensitive to water, and the gelation process is complicated, which cannot be effectively controlled, and it is easy to crack during the drying process

At present, many methods adopt the composite method of additives to prepare alumina-based airgel materials. CN103342537B discloses a method of in-situ water generation to control the hydrolysis and polycondensation of aluminum alkoxides. Although it can be effectively controlled, its The process is complex, and both acetone and aniline are toxic, which increases the cost and risk. At the same time, the drying treatment in the later stage is also a composite process, and pure alumina airgel is not well prepared; CN103482663A discloses a method using Alcohol dehydration method is used to prepare alumina airgel, but the process is long, and it takes several days to allow alcohol to be dehydrated automatically to meet the needs of hydrolysis and polycondensation, which cannot meet the needs of large-scale production

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