Co(2)MnO(4)/Ce(0.8)Tb(0.2)O(2-δ) Dual-Phase Membrane Material with High CO(2) Stability and Enhanced Oxygen Transport for Oxycombustion Processes.

Oxygen transport membranes (OTMs) are a promising oxygen production technology with high energy efficiency due to the potential for thermal integration. However, conventional perovskite materials of OTMs are unstable in CO(2) atmospheres, which limits their applicability in oxycombustion processes. On the other hand, some dual-phase membranes are stable in CO(2) and SO(2) without permanent degradation. However, oxygen permeation is still insufficient; therefore, intensive research focuses on boosting oxygen permeation. Here, we present a novel dual-phase membrane composed of an ion-conducting fluorite phase (Ce(0.8)Tb(0.2)O(2-δ), CTO) and an electronic-conducting spinel phase (Co(2)MnO(4), CMO). CMO spinel exhibits high electronic conductivity (60 S·cm(-1) at 800 °C) compared to other spinels used in dual-phase membranes, i.e., 230 times higher than that of NiFe(2)O(4) (NFO). This higher conductivity ameliorates gas-solid surface exchange and bulk diffusion mechanisms. By activating the bulk membrane with a CMO/CTO porous catalytic layer, it was possible to achieve an oxygen flux of 0.25 mL·min(-1)·cm(-2) for the 40CMO/60CTO (%(vol)), 680 μm-thick membrane at 850 °C even under CO(2)-rich environments. This dual-phase membrane shows excellent potential as an oxygen transport membrane or oxygen electrode under high CO(2) and oxycombustion operation.