NaA zeolite as an effective diffusion barrier in composite Pd/PSS membranes

Palladium composite membranes on porous stainless steel were prepared by electroless plating. In order to obtain a thin palladium film, an intermediate layer was necessary to modify the pore size of the substrate and form a diffusion barrier between the palladium film and the support. The NaA zeolite, used as intermediate, was synthesized by vacuum-assisted secondary growth. Pure gas permeability tests were conducted using hydrogen and nitrogen between 400 and 450 °C. The surface morphology and the components of the different layers of the membrane were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). When vacuum was applied during the zeolite synthesis at 80 °C, the Pd membrane showed high H2/N2 ideal selectivity in the working temperature range. This result suggests that NaA zeolite is an effective intermediate substrate modifier when an appropriate synthesis method is employed.