Ceramic membranes - characterization and applications

A combination of characterization techniques for the pore structure of meso - and microporous membranes is presented. Equilibrium (sorption and Small A ngle Neutron Scattering) and dynamic (gas relative permeability through mem branes partially blocked by a sorbed vapor) methods have been employed. Cap illary network and EMA models combined with aspects from percolation theory can be employed to obtain structural information on the porous network top ology as well as on the pore shape. Model membranes with well defined struc ture formed by compaction of non-porous spherical particles, have been empl oyed for testing the different characterization techniques. Attention is dr awn to the need for further development of more advanced sphere-pack models for the elucidation of dynamic relative permeability data and of Monte-Car lo Simulation for the analysis of equilibrium sorption data from microporou s membranes. The application of ceramic membranes in separations of condensable from non -condensable vapors is explored both theoretically and experimentally. Capi llary condensation greatly enhances the permeability of the condensable vap or through the mesoporous membrane resulting in large selectivities over no n-condensable vapors. Attention is drawn to the fact that the dynamic membr ane properties depend on a wider range of microstructural characteristics, relevant to the separation efficiency of the membrane. Therefore, measureme nts of the dynamic relative permeability and of condensable vapor permeabil ity provide significant saving in effort for the determination of the optim um pressure and temperature operation conditions and for the development of a model predicting the membrane performance.