Perovskite-type B-site Bi-doped ceramic membranes for oxygen separation

Novel mixed conducting oxides, B-site Bi-doped perovskites were exploited a nd synthesized. Cubic perovskite structures were formed for BaBi0.2COyFe0.8 -yO3-delta (y less than or equal to 0.4) and BaBixCo0.2Fe0.8-xP3-delta (x=0 .1-0.5) The materials exhibited considerable high oxygen permeability at hi gh temperature. The oxygen permeation flux of BaBi0.2Co0.35Fe0.45O3-delta m embrane reached about 0.77 x 10(-6) mol/cm(2) s under an air/helium oxygen partial pressure gradient at 900 degrees C, which was much higher than that of other bismuth-contained mixed conducting membranes. The permeation flux es of the materials increased with the increase of cobalt content, but no a pparent simple relationship was found with the bismuth content. The materia ls also demonstrated excellent reversibility of oxygen adsorption and desor ption. Stable time-related oxygen permeation fluxes were found for BaBi0.2C O0.35Fe0.45O3-delta and BaBi0.3Co0.2Fe0.5O3-delta a membranes at 875 degree s C.