Aerogel overview:

Aerogel is a porous nanomaterial with high specific surface area and low bulk density. Due to the unique nanostructure of aerogel, it has broad application prospects in aerospace, catalysis, environmental protection and other fields. Its preparation technology has become an emerging field of chemical engineering research. Sol-gel method (Sol-gel) is a commonly used method to prepare aerogels, which includes three processes: sol preparation, gel preparation and gel drying.

The drying process of 　　 gel is one of the important processes. Traditional drying methods have the following adverse effects on the preparation of aerogels: the basic particles of the material become coarser, the specific surface area is greatly reduced, and the pores are greatly reduced. The supercritical fluid drying technology (Supercriticalfluiddrying, SCFD) developed in recent years will not produce such adverse effects.

Because the supercritical fluid has the properties of both gas and liquid, there is no gas-liquid interface, so there is no surface tension. At this time, there is no additional pressure generated by surface tension in the capillary pores of the gel. Therefore, drying the gel under supercritical fluid conditions will not produce the collapse of the gel structure caused by additional pressure, avoid the shrinkage of the gel during the drying process, and maintain the gel network framework structure. Ultrafine aerogel with high specific surface area, uniform particle size distribution, and large pore volume.