Because of ultralow thermal conductivity, excellent catalytic activity, and better heat resistance than silica aerogel, alumina-based aerogel has drawn great interest as thermal insulators and catalysts. However, it is too fragile and sinters above 1000°C (it shrinks drastically, >50%, and leaves the surface area as low as 10−70 m 2 /g at 1300°C), which badly limits its high-temperature applications. Herein, super heat-resistant, strong alumina aerogels are prepared via a novel acetone-aniline in situ water formation (ISWF) method combined with novel modification techniques: supercritical fluid modification (SCFM) and hexamethyldisilazane gas phase modification. The heat resistance of alumina aerogel is enhanced up to 1300°C via this method. The shrinkage of the optimized alumina aerogel is reduced to as low as 1 and 5% and the corresponding surface area reaches up to 152−261 and 125−136 m 2 /g after being heated to 1200 and 1300°C for 2 h, respectively. The strength is significantly increased by more than 120% through SCFM. It also exhibits excellent thermal insulation properties at temperatures up to 1300°C. This may significantly contribute to their practical ultrahigh-temperature applications in thermal insulations, catalysts, catalyst supports, etc.

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Robust, highly thermally stable, MO x /(MO x − SiO 2 )/SiO 2 core−shell nanostructured metal oxide aerogels with a MO x core and (MO x −SiO 2 )/SiO 2 shell are produced via novel alkoxide chemical liquid deposition techniques. The core−shell nanostructure not only significantly reinforces the nanoparticles but also effectively inhibits the crystal growth and phase transition of metal oxide upon heat treatment, which enhances the heat resistance from approximate 400− 800°C up to 1000−1300°C. The resultant core−shell nanostructured Al 2 O 3 , ZrO 2 , and TiO 2 aerogels can support at least 5800 times their weight and exhibit high surface areas of 139, 186, and 154 m 2 /g after fired at 1300, 1000, and 1000°C, respectively, which are the highest surface areas for metal oxide aerogels ever reported. We demonstrate that the core−shell ZrO 2 and TiO 2 aerogels show enhanced adsorption and photocatalytic performances, respectively, for dye after fired at 1000°C. The core−shell Al 2 O 3 aerogel/mullite fiber/TiO 2 composite possesses ultralow thermal conductivities of 0.058, 0.080, and 0.11 W/mK at 800, 1000, and 1200°C, respectively, which are the lowest values for inorganic aerogels ever reported. The resulting materials are promising candidates as hightemperature (400−1300°C) thermal superinsulators, adsorbents, and catalysts.