Palladium Based Inorganic Hollow Fibre Membranes

In the last decade, porous alumina substrates in hollow fibre configuration have attracted substantial interest as substrates for coating Pd and Pd-alloy membranes. This is due to the high area/volume ratio in comparison to other configurations, leading to much higher hydrogen permeation rates per unit. The substrates were prepared using conventional extrusion techniques, resulting in symmetric structures which usually exhibit large gas permeation resistance. Furthermore, surface modification such as the deposition of a γ-Al2O3 is required to smooth the substrate surface prior to the deposition of a Pd layer. However, the surface treatment complicates the overall fabrication processes and eventually increases in the total production cost. In this book, Al2O3 hollow fibres with different asymmetric macrostructures, i.e.various thickness ratios between a finger-like layer and a sponge-like layer, have been prepared by a phase inversion/sintering technique. Such asymmetric hollow fibres are used as substrates onto which a Pd membrane is deposited directly by an electroless plating (ELP) technique without any pre-treatment of the substrate surface.