(173h) Pd/Ta Composite Metallic Membranes for High Purity Hydrogen Separation: Permeability and Durability

Hydrogen is considered as one of the clean energy carrier, but still, more than 90% of hydrogen is produced from hydrocarbon reforming processes involving a hydrogen purification step. Dense metallic membranes are drawing attention as a high purity hydrogen separation technique either as a stand-alone purification unit or to be used with catalyst as a membrane reactor to replace a series of end processes. Palladium based thin metallic membranes have been intensively developed due to their stable nature, but they are costly and permeability is significantly lower than that of body centered cubic (BCC) metal based membranes . In this study, as an effort to overcome this problem, Tantalum/Palladium (Ta/Pd) composite membrane has been fabricated using electroless deposition of Pd on a chemically treated Ta tube. The amount of palladium is significantly reduced while maintaining high permeability of Tantalum. The fabricated membrane had permeability value higher than that of the best Pd based metallic membrane reported, with hydrogen purity of 99.999% under mixed gas operations including N2, CO2, CO, H2O. It was possible to operate the membrane in a desired temperature range of 400 °C ~500 °C with no failure due to hydrogen embrittlement. Durability behavior of the membrane has been evaluated as a function of operating temperature and hydrogen flux, and optimal operating conditions are suggested as a function of Pd thickness.