Preperation And Hydrogen Permeation Of Proton Conductor Ceramic Membrane

High-temperature proton conducting ceramic membrane, also named as high-temperature hydrogen ion conducting ceramic membranes, is a kind of fast ionic conductor with protons as it charge carriers.It is a species of important functional material. In this paper,we prepared BaCeo.95Tb0.05O3-a(BCTb)ceramic powder, fabricated BCTb hollow fiber membranes,and manufactured BCTb and Ni-BCTb symmetrical ceramic membranes and Ni-BCTb asymmetrical ceramic membranes. In order to grasp the properties of ceramic powder, hollow fiber membranes and ceramic membranes, we systematically carried on SEM, XRD, inductivity and hydrogen permeation measurement,et c.Firstly, sol-gel and low temperature combustion methods were used to prepare BCTb ceramic powder,and then phase inversion and sintering technologies were adopted to manufacture BCTb hollow fiber membranes. The dense symmetrical BCTb ceramic membranes were fabricated through static press and sintering technologies. In order to obtain gas-tight hollow fibres with sufficient mechanical strength, the sintering temperature should be controlled between1350℃and1450℃. The indensity of both hollow fibre membranes and membranes improved when the sinter temperature were elevated.The maximum hydrogen permeation flux through the symmetric Ni-BCTb membrane reached up to0.013μmol·cm-2·s-1(0.018mL-min-1·cm-2) at950℃when using the20%H2/N2mixture feed and He as thesweep gas, respectively. Hydrogen permeation through the BCTb hollow fibre membranes was carried out between700℃and1000℃using50%H2-He mixture as feed on the shell side and N2as sweep gas in the fibre lumen. The measured hydrogen permeation flux through the BCTb hollow fibre membranes reached up to0.422μmol·cm-2·s-1at1000℃when the flow rates of the H2-He feed and the nitrogen sweep were40mL-min-1and30mL-min-1,respectively. The long-term operation test indicates that the BCTb hollow fiber membranes were stable for hydrogen permeation although the phase decomposition of theBCTb perovskite was occured. The oxygen permeation proved that the BCTb hollow fiber membranes were not suitable for oxygen permeation metarials.Secondly, the Ni-BCTb symmetrical and asymmetrical ceramic membranes were obtained by the methods of static press and sintering technologies. The XRD, SEM, conductivity and hydrogen permeation tests were proceeded. The electrical conductivity of the Ni-BCTb membranes approached to400S·cm-1at room temperature but decreased with increasing temperatures. The maximum hydrogen permeation flux through the asymmetric Ni-BCTb membrane with a90μm separation top layer integrated with a porous substrate had reached up to0.914mL·cm-2·min-1at850℃when using the50%H2/N2mixture feed and He as the sweep gas, respectively. The surface exchange reaction kinetics took a controlling effect on the hydrogen permeation through the membrane. The long-term operation test indicated that the Ni-BCTb cermet membranes were not sufficiently stable for hydrogen permeation due to the phase decomposition of the BCTb perovskite.