Preparation of dense La0.5Sr0.5Fe0.8Cu0.2O3-δ-(Li,Na)2CO3-LiAlO2 composite membrane for CO2 separation

Dense La0.5Sr0.5Fe0.8Cu0.2O3-delta-(Li,Na)(2)CO3 and La0.5Sr0.5Fe0.8Cu0.2O3-delta-(Li,Na)(2)CO3-LiAO(2) composite membranes were prepared for CO2 separation. The La0.5Sr0.5Fe0.8Cu0.2O3-delta (LSFCu) was prepared via the combined EDTA-citrate complex sol-gel process according to a previous study and then used in the synthesis of the dual phase membrane. XRD characterisation of the La0.5Sr0.5Fe0.8Cu0.2O3-delta sample showed it is orthorhombic structure with space group Pnma(62), a=5.4784(5) angstrom, b=7.7456(7) angstrom, c = 5.5014(5) angstrom, and V=233.44(4) angstrom(3). Dense composite membrane was obtained after carbonate treatment. Mixed CO2/N-2, CO2/O-2 and CO2/ air gases were used for CO2 permeation experiments. At 750 degrees C, high CO2 permeation rate of 1.55 ml cm(-2) min(-1) was observed for the LSFCu-(Li,Na)(2)CO3-LiAlO2 composite membrane when 20% CO2/80% O-2 mixture was used as the feed gas. Introduction of similar to 10 wt% LiAlO2 in the oxide-carbonate composite results in increased CO2 permeation rates which is likely due to the enhancement in surface reaction. The dominant pathway for CO2 permeation in the LSFCu-(Li,Na)(2)CO3-LiAlO2 composite membrane was believed through the coherent interaction between O2- and CO32- ions. Increased oxygen partial pressure in the feed gas can facilitate CO2 permeation. Due to the low O-2 concentration in real flue gases, potentially the LSFCu-(Li,Na)(2)CO3-LiAlO2 dual phase membrane will separate CO2 only which provides an alternative technology for CO2 separation. (C) 2014 Elsevier B.V. All rights reserved.