Synthesis of a novel Al2O3-SiO2 composite aerogel with high specific surface area at elevated temperatures using inexpensive inorganic salt of aluminum

We have developed a new sol gel route to synthesize Al2O3-SiO2 composite aerogel using inexpensive inorganic salt of aluminum. The approach, which is straightforward, inexpensive, and safe, can be employed to produce a monolithic mesoporous material with a high specific surface area, which is heat-treated at high temperatures. The results show that SiO2 is essentially amorphous, whereas Al2O3 predominately exists as polycrystalline boehmite which consists of fibrous particles and web-like microstructures. As the heat treatment temperature increases to 600 degrees C, the structural transition from boehmite to gamma-Al2O3 occurs within the composite. When the composite is heat-treated at 1100 degrees C, SiO2 crystallization occurs and the mullite phase begins to appear. The specific surface area decreases with an increase in heat treatment temperatures; however, it remains 120 m(2)/g until 1200 degrees C. The heat treatment process improves the quality of the three-dimensional aerogel network, and the pore distribution becomes uniform after heat treatment. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.