A chemically stable La0.2Sr0.8Fe0.9Mo0.1O3-δ-molten carbonate dual-phase membrane for CO2 separation

Abstract

We report here a mixed oxygen ionic-electronic conductor-molten carbonate composite membrane for high temperature CO2 separation. Mo-doping at Fe-site of La0.2Sr0.8FeO3-δ (LSF) is attempted to address its stability issue in CO2 or carbonate-containing environment. The La0.2Sr0.8Fe0.9Mo0.1O3-δ (LSFM)-molten carbonate membrane with 1 mm thickness delivers a CO2 permeation flux of 1.57 × 10−3 mol m−2 s−1 at 800 °C with 50% CO2 + 50 % N2 (total 1 atm) as feeding gas and pure He (1 atm) as sweeping gas, compared to 0.737 × 10−3 mol m−2 s−1 for the LSF counterpart. The CO2 permeation flux further increases to 2.25 × 10−3 mol m−2 s−1 for membrane prepared with Al2O3 coated LSFM substrate. An even higher CO2 permeability of 2.69 × 10−3 mol m−2 s−1 is demonstrated for LSFM-molten carbonate membrane at 800 °C when using simulated flue gas (15% CO2 + 10% O2 + 75 % N2 in total 1 atm) as feeding gas. The membrane also exhibits relatively stable CO2 and O2 fluxes during 50 h test at 750 °C. The designed LSFM-molten carbonate membrane can be potentially used as a reactor for dry methane reforming and partial oxidation of methane with flue gas as direct feedstock.