Synthesis of thermo-stable high surface area alumina powder from sol–gel derived boehmite

A simple sol–gel route was employed to generate high surface area boehmite using aluminum iso-propoxide (AIP), acetic acid (AA) and 2-propanol (IPA) as precursors. During hydrolysis molar ratios, i.e. H2O/AIP ∼4.0, IPA/AIP ∼19 and AA/AIP ∼0.02 were kept to get fibrous boehmite precursor with high surface area ∼442.9 m2 g−1 by digestion of precipitate at 80 °C for 20 h. The boehmite precursor, after calcination at 1100 °C for 5 h, was transformed into metastable phases of alumina with surface area of 68.7 m2 g−1 and pore volume of 0.62 cm3 g−1 and average pore diameter of 34.7 nm while a commonly used commercial one (CATAPAL-A) was transformed into only α-alumina phase having lower surface area of 9.1 m2 g−1 and pore volume of 0.10 cm3 g−1 with average pore diameter of 44.6 nm. The retention of high surface area in sol–gel derived alumina powder (as compared to that derived from the commercial CATAPAL-A boehmite precursor) is attributable to typical morphological features of as derived boehmite, i.e. fibrillar nature (confirmed by TEM) that are responsible in retarding sintering kinetics because of less number of contact points between the particles during calcination.