A mixed ionic and electronic conducting dual-phase membrane with high oxygen permeability

Area of Science:

• Materials Science
• Chemical Engineering
• Solid State Chemistry

Background:

• Developing advanced materials for efficient oxygen separation is crucial for various industrial processes.
• Mixed ionic-electronic conducting (MIEC) materials offer potential for high-performance membranes.
• Existing MIEC materials often face challenges with stability or conductivity.

Purpose of the Study:

• To develop a novel dual-phase membrane with enhanced chemical stability and oxygen permeability.
• To investigate the effect of copper doping on ceria-based materials for mixed conduction.
• To characterize the microstructure and performance of the developed CGCO-LCF membrane.

Main Methods:

• Fabrication of a dual-phase membrane using a one-pot method, combining Ce(0.85)Gd(0.1)Cu(0.05)O(2-δ) (CGCO) and La(0.6)Ca(0.4)FeO(3-δ) (LCF).
• Characterization of the membrane's microstructure, including the formation of an intergranular film.
• Measurement of oxygen permeation flux under high temperatures with CO2 as sweep gas.

Main Results:

• The CGCO-LCF membrane exhibited a high oxygen permeation flux of 0.70 mL min⁻¹ cm⁻² at 950°C for a 0.5 mm thick membrane.
• Copper doping in CGCO enhanced both ionic and electronic conductivity, facilitating mixed conduction.
• A unique intergranular film (2-10 nm) containing Ce, Ca, Gd, La, and Fe was observed between CGCO grains.
• The membrane demonstrated excellent stability in CO2, even at lower temperatures (800°C) during long-term operation.

Conclusions:

• The developed CGCO-LCF dual-phase membrane is a promising material for efficient and stable oxygen separation.
• The formation of the intergranular film plays a significant role in the membrane's enhanced properties.
• The study highlights the potential of copper-doped ceria-based composites for high-temperature membrane applications.