Arsenic Adsorption on Copper-Palladium Alloy Films

The adsorption of arsine on copper-palladium alloy films at 288^oC was studied by scanning electron microscopy with energy-dispersive X-ray methods (SEM-EDX) characterization.  The composition spread alloy film (CSAF) coupons were exposed to arsine in nitrogen in a small flow reactor.  The alloys containing predominantly copper (small concentrations of palladium) or predominantly palladium (small concentrations of copper) exhibited large surface concentrations of arsenic after exposure to arsine.  The arsenic present on the copper-rich alloy films is consistent with a Cu₃As phase, whereas the arsenic found on the palladium-rich alloy films are consistent with a PdAs₂ or AsPd₂ phases.  These results have potential consequences for the design of sorbents for the capture of arsenic from fluid streams, and for the stability of palladium-copper alloy membranes employed for hydrogen separation from coal-derived syngas.