CVD techniques for gas separation membranes synthesis - characterization - applications

Abstract
Membranes used in the separation of gas phase have found a number of important applications. In the past few years, the development of inorganic membranes, which have numerous advantages (thermal and mechanical stabilities, steam cleaning ability...) paved the way for high temperature applications. Inorganic membranes are widely used in gas separation processes such as reversible dehydrogenation reaction, O₂/N₂separation, CO₂ and volatil organic compounds recovery...Usually, inorganic membranes (SiO₂, Al₂O₃, TiO₂, ZrO₂, Pd...) are deposited on porous substrates in the sol-gel way. CVD techniques can be used as an alternative process for the deposition of very thin films in a wide range of temperature. The membranes deposited belong to the oxide, nitride, carbide and mixted metal compounds. We will present the different CVD techniques used in membranes synthesis : conventional CVD and OMCVD, counterdiffusion CVD, plasma assisted CVD. From a porous substrate, the CVD techniques lead to the pore diameter reduction or film deposition on the top of the membrane and plugs penetrating the pore entrance. Some examples of gas separation membranes coated by CVD will be developed.