Mixed ionic-electronic conducting composite-based ceramic-carbonate dense membranes for CO2/O2 counter-permeation and CO oxidation

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• Ce 0.80 Sm 0.15 Sr 0.05 O 2-δ -Sm 0.6 Sr 0.4 Al 0.3 Fe 0.7 O 3-γ was tested as membrane reactor. • The CO oxidation and CO 2 /O 2 counter-permeation were studied. • Membrane exhibits high oxygen ionic flux counter-permeation. • O 2 counter-permeation is the limiting factor in CO 2 permeation. • The electronic effect of Sm 0.6 Sr 0.4 Al 0.3 Fe 0.7 O 3 was analyzed. Dense inorganic membranes made of the ionic conductor Ce 0.80 Sm 0.15 Sr 0.05 O 2-δ and the electronic-ionic conductor Sm 0.6 Sr 0.4 Al 0.3 Fe 0.7 O 3-γ were infiltrated with molten carbonates. One side of the membrane is supplied with CO, and the opposite side is fed with O 2 . The CO oxidation and CO 2 /O 2 counter-permeation fluxes are studied as functions of temperature and weight percent of the mixed ionic-electronic conductor phase. The O 2 counter-permeation was correlated to the oxygen ionic flux counter-permeation consumed for CO oxidation and CO 3 2− formation for CO 2 permeation. The Ce 0.80 Sm 0.15 Sr 0.05 O 2-δ /Sm 0.6 Sr 0.4 Al 0.3 Fe 0.7 O 3 -molten carbonates system exhibits higher oxygen ionic flux counter-permeation than Ce 0.80 Sm 0.15 Sr 0.05 O 2-δ -molten carbonates system, producing a larger amount of CO conversion in the first case. The limiting factor for the O 2 counter-permeation and CO 2 permeation in triple-phase membranes is the oxygen ionic conductivity. In dual-phase membranes, the redox reaction for oxygen dissociation becomes vital for oxygen ionic flux. However, the limiting factor for the O 2 permeation flux is the oxygen ionic transport in the ceramic phase. On other hand, the limiting factor for the CO 2 permeation is attributed to both the ionic transport in the molten carbonates and the ceramic phase. The weight percent of the perovskite Sm 0.6 Sr 0.4 Al 0.3 Fe 0.7 O 3 was varied to study the effect of its electronic property on the CO 2 /O 2 counter-permeation flux and CO oxidation, establishing that the electronic nature of Sm 0.6 Sr 0.4 Al 0.3 Fe 0.7 O 3 enhances the formation of oxygen ions. This increases the carbonate ions concentration on the surface of the CO-supply membrane side, which raises the driving force for CO 2 permeation. Also, the CO 2 formation rate on the oxygen supply side is faster than on the CO-supply membrane side. The formation rate of molecular oxygen is lower than the CO 2 formation rate.