Characterizations of Pd–Ag membrane prepared by sequential electroless deposition

Palladium alloy membranes were prepared by sequential electroless plating steps on porous stainless steel (PSS). Full characterizations of Pd–Ag/PSS composite membranes were performed using scanning electron microscopy (SEM), energy dispersive spectroscopic analysis (EDS), atomic force microscopy (AFM) and X-ray diffractometry (XRD). AFM images show that in the electroless plating process lower skin layer roughness and lower deposition rate were related. Although electroless plating was conducted in a sequential process, the deposit over and inside of porous substrate was homogenous as analyzed by EDS analysis. Therefore, the deposited Pd–Ag alloy membrane retained the same composition over and through the porous substrate. The porous structure of composite membranes was also characterized by the gas permeability technique. From the experimental results, it can be concluded that a combined mechanism of Knudsen diffusion and viscous flow was conducted in the porous membrane.