Hydrogen permeability of sulfur tolerant Pd–Cu alloy membranes

Abstract

H2 permeation through Pd–Cu alloy membranes was carried out using pure H2, simulated syngas, and binary H2 gas mixtures of N2, CO, CO2, or H2O, respectively, along with and without H2S in the feed to investigate the impact of non-hydrogen gas species on H2 permeability at temperatures between 350°C and 500°C under pressures from 2.03bar to 13.79bar. When H2S was added to the feed, the H2S concentration was varied from 5ppmv to 39ppmv. The testing results indicated that the H2 permeability through the Pd–Cu alloy membranes from pure H2 followed Sievert's law. H2S in the feed did not affect the H2 permeability at H2S concentrations below 39ppmv and temperatures between 400°C and 500°C, indicating that the Pd–Cu separator was sulfur tolerant. From the H2 permeation experiments with H2 gas mixtures, it appeared that no inhibition effect from N2, CO, CO2 and H2O on H2 permeation was observed at temperatures between 400°C and 500°C. However, the inhibition effect from N2, CO and H2O on the H2 permeation was observed at 350°C. Furthermore, the Pd–Cu separator was tested for 1031h including 618h exposure to 5–39ppmv H2S and showed stable H2 permeation flux without N2 leakage detected, suggesting that the separator had a good thermal and structural stability.