A tailor-made porous stainless steel support for a dense hydrogen separation membrane

A tailor-made DPSS (disc-shaped porous stainless steel substrate) for a thin and dense hydrogen membrane with high performance was fabricated by molding pre-treated metal powder, sintering an ingot and then slicing by electrical discharge machining. The sliced DPSS has a diameter of 50.8 mm and a thickness of 1.6 mm. In comparison with commercially produced support (DPSS-M), the sliced DPSS, having surface roughness of 2.7, maximum surface pore size of about 2 μm, porosity of 33.1% and average pore diameter of 0.58 μm, is more suitable as the support for the thinner Pd membrane. The hydrogen membrane with Pd layer of 4.4 μm was prepared and its performance was evaluated. It was shown that the Pd/DPSS membrane had a higher H2/N2 selectivity (3825) with a hydrogen flux of 24.7 ml/min/cm2, than that of Pd/DPSS-M (1821), at del-P = 1 and 400 °C, even though the surface morphologies of DPSS had been modified with less steps than DPSS-M. For CO2/H2 separation, the Pd/DPSS membrane enriched 40% CO2 to 90.8% and separated 60% H2 to 99.8% at 400 °C and del-P = 20 bar.