Dual-phase membranes consisting of a mixed ionic-electronic conducting ceramic phase and an ionically conductive molten carbonate phase have the ability to selectively separate CO2 at high temperature with or without the presence of O2. This study examines the stability of a dual-phase ceramic-carbonate membrane consisting of La0.6Sr 0.4Co0.8Fe0.2O3-δ (LSCF) and an eutectic molten carbonate phase composed of Li2CO3, Na2CO3, and K2CO3. LSCF-carbonate membranes exposed to a CO2/N2 gradient at temperatures between 800 and 900 C result in a drastic decrease in CO2 permeation before reaching steady-state after more than 60 h of exposure to the permeating gases due to a surface reaction between CO2 and the LSCF ceramic phase of the membrane, resulting in decomposition of the membrane surface. The introduction of O2 in the feed gas, however, helps maintain the LSCF ceramic phase structure and results in stable CO2 permeation flux at a much higher value due to a change in transport mechanism in the membrane. The results suggest that it is critical to find oxygen ionic or mixed-conducting ceramic materials that are stable in CO2 environments in order to ensure stability of the membrane for CO2 permeation.
ASJC Scopus subject areas
- Chemical Engineering(all)
- Industrial and Manufacturing Engineering