Preparation of High-Temperature Resistant Aerogels by Incorporating Aluminum Sol into Composite Silica Sources Using Ambient Pressure Drying

To reduce production costs and enhance the high-temperature resistance of SiO2aerogels, an aluminum-doped silica aerogel (ASA) was successfully prepared using the sol-gel method and atmospheric drying method. The composite silica sources included TEOS and inexpensive acidic silica sol, while the aluminum source was aluminum sol. The study investigated the influence of the molar ratio of acidic silica sol to TEOS, Al/Si, and calcination temperature on the composition, structure, and high-temperature resistance of the ASA. The results indicate that a sample with an acidic silica sol to TEOS molar ratio of 0.8 achieved a specific surface area of 683.204 m2·g−1. The Al/Si molar ratio significantly impacted the high-temperature resistance of the ASA, with the sample having a molar ratio of 0.02 Al/Si displaying the highest specific surface area of 705.956 m2·g−1at 600 °C. Moreover, this surface area remained at 273.099 m2·g−1after calcination at 1000 °C, notably higher than the sample without aluminum sol (16.082 m2·g−1). Mechanism analysis indicated that the addition of aluminum sol to the SiO2aerogel inhibited phase transitions, and both acidic silica sol and aluminum sol particles enhanced the aerogel structure, contributing to a marked improvement in high-temperature resistance.