(401at) Characterization of Composite Pd/Ta Metallic Membranes for Hydrogen Separation

Hydrogen has been considered as an alternative energy carrier as increasing demands of clean energy processes, which could circumvent environmental problems. Gasifier processes are widely used to mass production of hydrogen, but hydrogen produced from catalytic reactions contains massive amount of impurity components such as CO₂. Separation processes using hydrogen selective metallic membranes are considered a promising method for the production of high-purity hydrogen, and especially, Palladium (Pd) based membranes have received great attention because of its high hydrogen permeability and good selectivity at high temperature. In this study, commercial Tantalum (Ta) tube was treated by electroless plating method and fabricated Pd/Ta composite membranes. Prepared membranes were firstly evaluated their hydrogen permeability at different feed composition, reaction temperature and pressure conditions. The diffusion coefficient and surface reaction parameters as a function of membrane thickness and temperature were also calculated by numerical models. The Pd/Ta composite membranes showed high permeability at between 400 and 500 °C and CO-free hydrogen could be obtained from the mixed gas composition. Also, the performance of the Pd/Ta composite membranes could be improved by controlling the thickness of Pd and Ta layers, and the rate-determining step for hydrogen flux through metallic membrane was suggested by the numerical approaches.