Preparation of γ-A12O3 composite membrane and examination of membrane defects

A boehmite sol with a narrow particle size distribution and most probable diameter of 35 nm was prepared by peptization of boehmite suspension with HNO3. An unsupported γ-Al2O3 membrane made from the above sol possessed a narrow pore size distribution, with an average pore size of 4.8 nm and 320 m2/g specific surface area. A supported γ-A12O3 membrane produced by repeating dipping-drying-calcination procedure twice was proven to be defect-free by gas permeation measurements and SEM.