Preparation of thin (∼2 μm) Pd membranes on ceramic supports with excellent selectivity and attrition resistance

Abstract

Thin (∼2 μm) Pd membranes were prepared by two-step electroless plating (ELP) method on porous ceramic supports for hydrogen purification. The two-step ELP method consists of the first ELP, the heat treatment (923 K, N2 and 24 h) and the second ELP. The Pd composite membranes have been characterized by permeation tests with pure gas at 623–873 K and exhibited stable and highest hydrogen permeation flux (∼0.853 mol H2 m−2 s−1) and H2/N2 selectivity (∼88,465) at 823 K under a pressure difference of 0.1 MPa. The Pd composite membranes have been characterized by permeation tests with gas mixtures (H2/N2, H2/CO2) at 623–823 K. The effect of N2 on the hydrogen permeation flux of composite membranes was mainly due to the concentration polarization, and the effect of CO2 was due to concentration polarization at lower temperature (623 K) and a combination of the concentration polarization and chemical reactions at high temperatures (723 and 823 K). The Pd composite membranes have been characterized by attrition resistance tests with particles at 823 K and exhibited high hydrogen permeation stability and H2/N2 selectivity.