Palladium and palladium alloy membranes for hydrogen separation and production: History, fabrication strategies, and current performance

• Published in: Separation and purification technology 2010-05, Vol.73 (1), p.59-64
• Main Authors: Hatlevik, Øyvind, Gade, Sabina K., Keeling, Matthew K., Thoen, Paul M., Davidson, A.P., Way, J. Douglas
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemical engineering; Electroless plating; Exact sciences and technology; Hydrodynamics of contact apparatus; Hydrogen separation; Palladium alloy membrane; Stainless steel substrate
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2009.10.020

Our aim is to survey the state-of-the-art in the development of palladium and palladium alloy membranes for hydrogen separations and hydrogen production. At the time this paper was written, several research groups have developed palladium and/or palladium alloy membranes with pure hydrogen permeances approaching 0.01 mol/m 2 s Pa 0.5. This includes our work to prepare Pd and Pd alloy composite membranes on stainless steel porous substrates with zirconia diffusion barriers. A 0.93 μm thick pure Pd composite membrane on a Pall AccuSep ® stainless steel substrate achieved a pure hydrogen flux of 1.3 mol/m 2 s at 400 °C and 1.38 bar differential pressure. The hydrogen flux values we have measured compare favorably to the U.S. DOE 2010 pure hydrogen flux performance target of 0.96 mol/m 2 s = 250 ft 3(STP)/ft 2 h at conditions of 400 °C and a differential pressure of 20 psi or 1.38 bar. Pd alloy composite membranes containing Au and/or Ag show higher hydrogen flux than pure Pd membranes, as expected from the literature. At these same DOE test conditions of 400 °C and 1.38 bar, the pure hydrogen flux for a 2.3 μm thick, Pd 95Au 5 composite membrane was 1.01 mol/m 2 s. Approximately the same pure hydrogen flux of 0.97 mol/m 2 s was measured for a thicker, 4.6 μm, Pd 80Ag 20 composite membrane at 400 °C and 1.38 bar, consistent with the higher permeability of the Pd–Ag alloy compared to pure Pd and Pd–Au. Ideal H 2/N 2 separation factors of these composite membranes ranged from 337 to over 80,000.