Thermochemically stable ceramic composite membranes based on Bi₂O₃ for oxygen separation with high permeability

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Ceramic oxygen separation membranes are crucial for reducing CO2 emissions in oxy-fuel combustion power generation.
• Existing Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) membranes exhibit high oxygen permeability but lack long-term stability, particularly under CO2 exposure.

Purpose of the Study:

• To develop and characterize a novel ceramic composite membrane with enhanced stability and comparable oxygen permeability to BSCF.
• To evaluate the performance of the new membrane under various temperature and CO2 sweep gas conditions.

Main Methods:

• Fabrication of a ceramic composite membrane using 60 vol% (Bi0.8Tm0.2)2O3-δ (BTM) and 40 vol% (La0.8Sr0.2)0.99MnO3-δ (LSM).
• Measurement of oxygen flux at different temperatures (down to 600 °C) and membrane thicknesses.
• Long-term stability testing at 750 °C for one month and at 700 °C with 50% CO2 sweep gas for over two weeks.

Main Results:

• The BTM-LSM composite membrane achieved oxygen fluxes of 1.01 mL min-1 cm-2 (1.35 mm thickness) and 1.33 mL min-1 cm-2 (0.75 mm thickness) at 900 °C.
• Significant oxygen fluxes were observed even at temperatures as low as 600 °C.
• The membrane demonstrated stable operation for extended periods, with minimal flux changes under demanding conditions.

Conclusions:

• The novel BTM-LSM ceramic composite membrane presents a promising alternative to BSCF for CO2 separation in fossil fuel power generation.
• This material offers a compelling combination of high oxygen permeability and superior long-term stability, addressing key limitations of current technologies.