A Mixed Ionic and Electronic Conducting Dual-Phase Membrane with High Oxygen Permeability

• Published in: Angewandte Chemie International Edition 2015-04, Vol.54 (16), p.4847-4850
• Main Authors: Fang, Wei, Liang, Fangyi, Cao, Zhengwen, Steinbach, Frank, Feldhoff, Armin
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Conduction; Conduction heating; electronic conductors; Electronics; ionic conductors; Membranes; oxygen transport; Penetration; Permeability; Permeation; Phase boundaries
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201411963

To combine good chemical stability and high oxygen permeability, a mixed ionic‐electronic conducting (MIEC) 75 wt % Ce0.85Gd0.1Cu0.05O2−δ‐25 wt % La0.6Ca0.4FeO3−δ (CGCO‐LCF) dual‐phase membrane based on a MIEC–MIEC composite has been developed. Copper doping into Ce0.9Gd0.1O2−δ (CGO) oxide enhances both ionic and electronic conductivity, which then leads to a change from ionic conduction to mixed conduction at elevated temperatures. For the first time we demonstrate that an intergranular film with 2–10 nm thickness containing Ce, Ca, Gd, La, and Fe has been formed between the CGCO grains in the CGCO‐LCF one‐pot dual‐phase membrane. A high oxygen permeation flux of 0.70 mL min−1 cm−2 is obtained by the CGCO‐LCF one‐pot dual‐phase membrane with 0.5 mm thickness at 950 °C using pure CO2 as the sweep gas, and the membrane shows excellent stability in the presence of CO2 even at lower temperatures (800 °C) during long‐term operation. A dual‐phase membrane made of two different mixed ionic–electronic conductors (MIEC) is presented. This composite mechanism enhances the rate of surface exchange and bulk diffusion for oxygen permeation at the same time. TPB=triple phase boundary.