Enhancement of the Long-Term Permeance, Selectivity Stability, and Recoverability of Pd–Au Membranes in Coal Derived Syngas Atmospheres

Abstract

Two new large scale (200 cm2) composite Pd and Pd–Au membranes were prepared and tested in an actual coal derived, but desulfurized, syngas in order to further quantify permeance loss due to species other than sulfur and to determine the nature of the contaminants. As in our previous work, membranes were tested at the National Carbon Capture Center (NCCC) in Wilsonville, Alabama. Before the syngas test, the Pd and Pd–Au membranes had thicknesses of 7 and 6.6 μm, H2 permeances at 450 °C of 17.7 and 29.2 N m3 m–2 h–1 bar–0.5, and H2/He selectivities higher than 2700 and 160 000, respectively. The two membranes produced H2 at an exceptionally high purity level of 99.8–99.9%. The selectivity of the Pd–Au membrane was stable for over 473 h in an actual syngas atmosphere at 450 °C and 12.6 bar demonstrating the high robustness and suitability of these membranes in industrial environments. However, as seen in our previous study, the two membranes showed a decrease in H2 permeance upon syngas introduction (rangin...