Thin Pd membrane on a modified porous stainless steel tube: Al 2O3 particle size selection strategy

Abstract

Palladium (Pd) membranes for hydrogen separation were deposited on modified porous stainless steel (PSS) tubes using the electroless plating technique. This study explores the hydrogen permeance influenced by the effect of reducing the thickness of the Pd membrane using different sizes of Al2O 3 particles, 10 and 1 μm, to modify the pores on the PSS surface. The pore size on the surface of the PSS tubes modified with 10 μm Al 2O3 particles decreased from 10~20 μm to less than 5 μm, while the surface of the PSS, modified by 1 μm Al2O 3, was very dense and smooth. Generally, the supporting tubes with smaller pore size on the surface give thinner Pd membrane. The minimum thickness of a dense Pd membrane decreased from 35.1 to 16.2 μm when using 1 μm Al2O3 particles to modify the PSS tubes, but the maximum hydrogen permeance was enhanced from 15.3 to 34.7m3/m2h atm0.5 at 500°C by using 10 μm Al2O3 particles. This evidence demonstrated the hydrogen permeance has a trade-off between the porosity (effective passages) and thickness of the Pd membranes since both are influenced by the Al2O3 particle size used in the surface modification. These results suggested a promising and simple approach to produce a Pd membrane with high hydrogen permeance. © 2011 The Chinese Institute of Engineers.