Preparation of highly porous Al ₂ O ₃ aerogel by one‐step solvent‐exchange and ambient‐pressure drying

Abstract

Abstract This work presents the preparation of alumina aerogel via sol‐gel route utilizing ambient‐pressure drying. A novel and efficient solvent‐exchange process has been utilized as an alternative to conventional solvent‐exchange processes by directly boiling the hydro‐gel in solvent. High emphasis has been given in the selection of solvent based on polarity, boiling point, and specific gravity compared with water to facilitate efficient solvent‐exchange and reuse of the solvent. The ambient‐pressure‐dried alumina aerogel was thermally treated at temperature from 300°C‐1200°C to study the change in density, porosity, specific surface area, and microstructure along with crystalline properties. The ambient‐pressure‐dried alumina aerogel showed lower tapped density 0.108 g/cm 3 , specific surface area 519 m 2 /g, and total weight loss of 36.94% at 900°C. The degree of crystalline structure from amorphous was observed to increase with increase in thermal treatment temperature above 300°C, dominant above 700°C, whereas the transformation of bayerite γ‐Al(OH) 3 to boehmite γ‐AlO 2 H was observed at 150°C‐300°C and to γ‐Al 2 O 3 phase was observed at temperature of 300°C‐1200°C.