Microstructural characterization and gas permeation performance of freeze-cast alumina supports

One of the major challenges for obtaining asymmetric membranes has been the preparation of ceramic supports with tailored pore structures. The methods commonly used for processing these materials do not allow a fine control of the support structure, which may decrease their mass transport capacity. As a consequence, freeze-casting is a promising technique for obtaining supports with tailored pore structures and permeation behaviors. This work deals with the preparation of freeze-cast alumina macroporous supports. Different freezing routes and alumina powders were used in this study. It was correlated the effect of these parameters on the pore structure and permeation capacity of the obtained supports. It was shown that the isotropic layer observed at the samples bottom side plays a key role in their non-Darcian permeability. As far as we know, this is the first time that this approach is reported in the literature for freeze-cast samples.