Abstract
The focus of this article is to study preparation procedures used to make supported palladium (Pd) membranes for hydrogen separation. We first modified the outside surface of a commercial porous stainless steel (PSS) tube by polishing and coating with a thin layer of alumina. This alumina layer serves to flatten the surface and also to act as a diffusion barrier between the Pd and PSS substrate. After modification, the Pd layer is then deposited using an electroless plating technique. Permeation analysis results indicate that the average pore size decreases from the original 17 μm to about 1.5 μm after modification. A dense Pd film can be obtained after only four times of electroless deposition. The selectivity of this Pd/Al 2 O 3 /PSS tube (length 5 cm, outside diameter 0.95 cm) is 110 for H 2 /N 2 , and the hydrogen permeance is 2.2 x 10 -7 mol/m 2 -s-Pa at 350 °C under a transmembrane pressure difference of 1.0 x 10 5 Pa.