Titania aerogel prepared by low temperature supercritical drying

Mesoporous titania aerogel with high surfaces area (1086 m(2) g(-1)) were prepared by two steps: heterogeneous precipitation of aqueous solution containing TiOSO4 and ammonia, followed by continuous supercritical extraction with CO2 after replacement of the water with n-propanol/benzene mixture. The total pore volume of as obtained aerogel is 3.44 cm(-3) g(-1) and the main pore diameter is 20-80 nm. The structure evolution of titania aerogel during heating was studied by DTA and high temperature XRD analyses. At 450 degrees C titania aerogel transforms to polycrystalline anatase. The morphology and microstructure characteristics of both titania aerogel and anatase samples were obtained by SEM, HRTEM, BET and BJH methods. Anatase reveals high photocatalytic activity during the degradation of 4-chlorophenol in aqueous suspension. (c) 2005 Elsevier Inc. All rights reserved.