Ionic conducting ceramic and carbonate dual phase membranes for carbon dioxide separation

• DOI: 10.1016/j.memsci.2012.06.030
• Publication Date: 2012-06-23T16:33:30Z
• Authors: Zebao Rui; Matthew Anderson; Yongdan Li; Y.S. Lin
• Keywords: Lithium carbonate; Permeance; Carbonate Ion

Abstract A dense membrane consisting of two-phases: molten carbonate for the conduction of carbonate ions and Bi 1.5 Y 0.3 Sm 0.2 O 3 (BYS) for the conduction of oxygen ions, was synthesized and used for selective permeation of CO 2 at high temperatures. Since CO 2 is transported by CO 3 2− , these membranes provide infinite selectivity for CO 2 over other species such as Ar, He or N 2 .The dual-phase membranes were synthesized by the direct infiltration molten carbonate into porous BYS supports with internal surface modified with γ-Al 2 O 3 to improve the wettability. Permeation took a long time to reach a steady state at the initial stage of high temperature CO 2 separation due to the reversible phase transform of the oxygen ions conduction phase between the rhombohedral structure and cubic fluorite structure. The CO 2 permeation flux for the dual phase membrane increases with increasing temperature (500–650 °C) with apparent activation energy for CO 2 permeation of 113.4 kJ/mol. The CO 2 permeation flux increases with increasing sweep gas flow rate and reaches a value of 0.083 mL/cm 2 /min at 650 °C and helium flow rate of 125 mL (STP)/min. The BYS–carbonate membrane offers higher CO 2 permeance than carbonate dual-phase membranes with lithium–cobaltite or yttrium stabilized zirconia as the oxygen ionic conducting phase.