Porous ceramic membranes: preparation, transport properties and applications

The preparation and characterization of porous ceramic membranes is presented. These membranes consist of a macroporous support system, with or without a mesoporous intermediate layer, and a microporous top layer. For the macroporous support membranes two manufacturing routes are described: a conventional and a RBAO (Reaction Bonded Aluminium Oxide) route. The mesoporous γ-Al₂O₃ layer is obtained by means of a sol-gel dipcoating technique. Three microporous top layers are considered: SiO₂, Al₂O₃-pillared montmorillonite and Laponite. These top layers have different pore structures which results in different gas transport properties. A SiO₂ membrane can be used for H₂ removal from a gas mixture. Al₂O₃-pillared montmorillonite and Laponite membranes do not show specific gas separation properties. Dehydration of water/2-propanol mixtures by means of pervaporation also proved a different behavior for these microporous membranes.