Microstructural adjustment of Ni-BaCe_0.9Y_0.1O _3-δ cermet membrane for improved hydrogen permeation

Dense ceramic membranes are usually hybridized with an electronically conductive metallic phase to enhance their hydrogen permeation fluxes, thereby increasing the hydrogen-production efficiency of hydrogen separation membranes. Herein, the hydrogen-separation properties of membranes fabricated from cermets containing BaCe_0.9Y_0.1O_3-δ (BCY) as the proton-conducting ceramic phase and Ni as the electronic-conducting metal phase were investigated with respect to the compositions of the Ni-BCY mixture. Because the hydrogen permeability of a cermet membrane is seriously affected by microstructural parameters such as grain size and homogeneity of the cermet mixture used to fabricate it, we tried to optimize the microstructures and compositions of the Ni-BCY cermets by controlling their fabrication conditions. A high-energy milling process was employed to fabricate fine-grained, dense membranes that exhibited high levels of mixing homogeneity. From the adjustment of composition and microstructure of Ni-BCY composites, the hydrogen permeability of Ni-BCY cermet membranes can be significantly increased so that hydrogen fluxes of ~0.76 cm³/(min cm²) at 800 C can be achieved.