NANOSTRUCTURED MEMBRANE MATERIALS FOR PRODUCING HIGH-PURITY HYDROGEN

Pd-based membranes are used for separation and purification of hydrogen in steam reforming reactors. However, at sufficiently low temperatures (less than 200°C), the penetrating flux of hydrogen through the membranes can be limited by the kinetics of surface processes. In the present study, the developed Pd-Ag-Ru alloy membranes were activated with a nanostructured modifying coating to intensify the hydrogen flux. This coating consisted of Pd nanoparticles deposited on the membrane surface, which are capable of significantly increasing the active surface area. Significant intensification of the hydrogen flux was observed over the entire studied temperature range (25-100 °C), and the highest values of the penetrating flux density were demonstrated for the modified membranes – up to 6,3 mmol s–1 m–2 at 100°C. This result is due to the increased number of active centers on the membrane surface reactive with respect to hydrogen. Surface activation helps to reduce activation barriers and enhance catalytic activity. The developed membranes also demonstrated high and stable selectivity over a long period of time. The strategy of modifying membrane materials with nanostructured coatings can shed new light on the development and production of durable and highly selective palladium-based membranes for steam-gas reforming reactors.