To produce a multifunctional silica aerogel with excellent stability under humid and high-temperature conditions, bifunctionalized hybrid silica aerogels (BHSAs) were created by a simple and eco-friendly self-catalyzed sol-gel process. BHSA can be used for thermal insulation and CO₂ capture with high durability with two functional groups including methyl and amine hybridized. The highest specific surface area (343 m²/g), pore volume (1.66 cm³/g), and surface amine content (2.14 mmol/g) were attained by TMA262 with an appropriate tetraethoxysilane (TEOS)/methyltriethoxysilane (MTES) molar ratio, as well as a water contact angle of 143°. TMA262 demonstrated high CO₂ adsorption capacity (1.87 mmol/g) and kinetics in humid 1% CO₂. With a low thermal conductivity at 25 ℃ (0.019 W/(m·K)), TMA262 exhibited outstanding thermal insulation over the temperature range stretching from −100 to 1300 ℃. Accelerated aging and thermal treatment indicated that TMA262 possessed excellent long-term stability for CO₂ capture and thermal insulation under humid and high-temperature conditions, and water played a significant role in CO₂ adsorption capacity. This study seamlessly integrates a diverse array of functionalities within the silica aerogel, offering significant guidance for the advancement of aerogels tailored for multi-scenario applications under extreme conditions.

The purpose of this study was to prepare a proof-of-concept CO₂ adsorbing material based on a new amine grafted silica aerogel microsphere (AGSAM) that could be used on both fixed and fluidized beds. A low-cost water glass and environment-friendly water were used as precursor and solvent of the silica aerogel, respectively. The silica aerogel microsphere (SAM) was prepared by dropping the siliceous solution into hot oil bath. The effect of the pH value of the siliceous solution, stirring speed and stirring paddle position on the sphericity and size of the SAM was investigated. The SAM with good sphericity was obtained when the pH value was 5.69–5.79. The mean diameter of the SAM decreased from 5 to 1 mm when the stirring speed increased from 1000 to 2000 rpm. The SAM with excellent sphericity was prepared when the paddle was placed on the top of the oil bath. When the paddle was placed at the middle and bottom of the oil bath, some liquid drops aggregated together and formed large aggregations. AGSAM was obtained by grafting the amine groups onto the framework of the silica gel microsphere. The CO₂ adsorption capacity of the AGSAM was 1.04 mmol g^-1 with 1% CO₂ at 300 mL min^-1. The AGSAM with 4, 3.2, 2 and 1 mm in diameters had the fluidizing velocities of 0.531, 0.425, 0.265 and 0.159 m s^-1, respectively. The AGSAM with different sizes met different fluidizing conditions.