Enhanced resistance of PdNiAu membranes under CO and H2S-containing streams

Abstract

Pd-based membranes offer energy efficiency and economic advantages, providing a promising route for hydrogen separation and recovery from several streams. Alloying Pd with other elements increases its resistance to corrosive gases while improving H2 permeability. This study investigated the permselective properties of PdNiAu membranes with different Ni contents (17, 23, and 27 at.% Ni) in pure H2 and under CO/He/H2 and H2S/H2 mixtures. The permselective properties were evaluated at different temperatures (573-723 K) and pressure differences across the membrane (ΔP: 10-100 kPa). The membranes studied exhibited promising H2 permeation properties; the highest permeability at 673 K and 100 kPa was obtained with the membrane containing 23 at.% Ni (2.1 x10-8 mol m-1 s-1 Pa-0.5). All membranes exhibited high H2/N2 selectivity (>10,000). Regarding chemical stability, the membranes with 23 and 27 at.% Ni, showed high tolerance to inhibition by CO and H2S. These results suggest that increasing Ni improves membrane performance in streams containing CO or S; however, the high chemical resistance of the membranes could be attributed to both Ni and Au.