Development and testing of thin composite palladium membrane for membrane fuel cell processors.
Chen, Chee Chong
MetadataShow full item record
The Palladium (Pd) based membranes have long been the focus of studies for the separation of hydrogen due to its high permeability and selectivity toward hydrogen. However, palladium is a precious metal and extremely expensive and its wider applications will depend largely on its ability to become economically feasible to compete with other separation technologies. Hence, the main focus of this study is to produce a supported, thin and defect free palladium composite membrane in a cost effective manner. This thesis also highlights some of current advances in palladium research, especially the membrane preparation methods. In this study, the Pd composite membranes were fabricated by depositing Pd metal as a thin layer by using advanced electroless plating coupled with partial suction method onto a 30nm -Al2O3 support. The suction pressure creates a pressure difference between the bore and tube side of the support and this will eventually encourage the transfer of more Pd metal onto the ceramic support, at the same time densifying the deposited layer and simultaneously prevent mass transfer from the film back into the solution, which is the major problem with conventional electroless plating techniques. The final membrane produced has a thickness of about 6 microns with flux in the order of ~0.1 mol/m2s and H2/N2 selectivity of 140 at 673K. The membrane also show its capability in purifying H2 gas using a reformate gas mixtures containing 67% H2, up to the value of 97.3% pure H2 in a single stage pass at 673K at low pressure differentials of 0.8 barg. Studies conducted also investigate the effects of electroless plating condition and parameters in their resulting relationship with the pore sizes of the ceramic support have on the palladium layer deposited.