Preparation of High Specific Surface Area Nano-Alumina by Vacuum Freeze Drying

Nano-alumina powders were prepared by vacuum freeze drying combined with reverse microemulsion method. The reverse microemulsion system consisted of cyclohexane/polyethylene glycol octylphenyl ether (Triton X-100)-hexadecyl trimethyl ammonium bromide (CTAB)/n-butylalcohol/water The morphology. structure, specific surface area, pore volume, and pore size of the alumina nanoparticles were characterized by scanning electron microscopy (SEM). transmission electron microscopy (TEM), X-ray diffraction (XRD), and specific surface area analysis The specific surface area of the alumina nanoparticles was about 550.0 m(2).g(-1) (changed with different reaction parameters) and the crystal structure was gamma-Al2O3. The particle size was very uniform and smaller than 10.0 nm The influence of different drying methods (normal hot-gas (hying, normal vacuum drying. vacuum freeze drying) and the main parameters of vacuum freeze drying on the physical properties of the product were studied Results showed that the nano-alumina powders obtained by vacuum freeze drying had much higher specific surface area and pore volume than that obtained by the two other drying methods. The specific surface area and pore structure of the nano-alumina were affected by the freezing rate, pre-freezing time, and drying time in the vacuum freeze drying process