Preparation and properties of Pd/Ag composite membrane for direct synthesis of hydrogen peroxide from hydrogen and oxygen

Pd and Pd–Ag alloy membranes on porous alumina tubes were prepared by means of simultaneous and sequential electroless plating technique. The characterizations of Pd–Ag composite membranes were performed using scanning electron microscopy (SEM), X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS). The catalytic reaction of H2 and O2 to directly form hydrogen peroxide was carried out in the membrane reactor at 293 K. The thickness of Pd–Ag alloy membranes obtained by simultaneous electroless plating was thinner than that by sequential electroless plating. And high uniformity of grains was found on the surface of the Pd–Ag membrane prepared by simultaneous electroless plating. The concentration of H2O2 increased with the increase in transmembrane pressure differences of hydrogen and a high concentration of H2O2 was obtained on the membrane which consists of a Pd layer on the surface of the membrane and a Pd–Ag alloy layer inside the membrane.