PdCuAu ternary alloy membranes: hydrogen permeation properties in the presence of H2S

ANA MARÍA TARDITI, CAROLINA IMHOFF, FERNANDO BRAUN, LAURA CORNAGLIA; JAMES MILLER, ANDREW GELLMAN

JOURNAL OF MEMBRANE SCIENCE

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2015 vol. 479 p. 246 - 255

0376-7388

PdCuAu ternary alloy membranes with different component compositions were synthesized by sequential electroless deposition on top of porous stainless steel substrates.  The ternary with the highest Au content, Pd69Cu14Au17, exhibited the highest hydrogen permeation flux, comparable to that of a Pd91Au9 membrane.  Upon exposure to 100 ppm H2S/H2 at 400°C for 24 h, all PdCuAu membranes experienced flux reductions of ~ 55 %, followed by recovery to ~ 80% of the initial hydrogen flux upon reintroduction of pure hydrogen at 400°C.  Complete flux recovery after H2S exposure required hydrogen treatment at 500°C.  XRD analysis of the H2S-exposed PdCuAu membranes revealed fcc alloy structure with no evidence of bulk sulphide formation.  In agreement with the XRD results, sulfur was not detected in the bulk of H2S-exposed samples by EDS.  However, analysis of H2S-exposed PdCuAu alloys by XPS-depth profiling revealed low, but measureable, amounts of sulfur in the near-surface region, about 10 nm in depth.  The depth profiles of samples after hydrogen recovery treatment showed significantly reduced sulfur content.  These results indicate that H2S exposure causes flux loss in PdCuAu alloys through a surface-poisoning mechanism, and that the surface sulfide can be removed?and flux recovered?by high temperature treatment in H2.