Ceramic membranes — characterization and applications

Abstract

ABSTRACT A combination of characterization techniques for the pore structure of meso-and microporous membranes is presented. Equilibrium (sorption and Small Angle Neutron Scattering) and dynamic (gas relative permeability through membranes partially blocked by a sorbed vapor) methods have been employed. Capillary network and EMA models combined with aspects from percolation theory can be employed to obtain structural information on the porous network topology as well as on the pore shape. Model membranes with well defined structure formed by compaction of non-porous spherical particles, have been employed for testing the different characterization techniques. Attention is drawn to the need for further development of more advanced sphere-pack models for the elucidation of dynamic relative permeability data and of Monte-Carlo Simulation for the analysis of equilibrium sorption data from microporous membranes. The application of ceramic membranes in separations of condensable from non-condensable vapors is explored both theoretically and experimentally. Capillary condensation greatly enhances the permeability of the condensable vapor through the mesoporous membrane resulting in large selectivities over non-condensable vapors. Attention is drawn to the fact that the dynamic membrane properties depend on a wider range of microstructural characteristics, relevant to the separation efficiency of the membrane. Therefore, measurements of the dynamic relative permeability and of condensable vapor permeability provide significant saving in effort for the determination of the optimum pressure and temperature operation conditions and for the development of a model predicting the membrane performance.