Study of CO2 permeation in Zn2+‐modified Al2O3‐carbonate membrane

Abstract

AbstractMolten carbonate‐based membranes for CO2 capture have received attentions because of their high CO2 selectivity, potential energy‐saving capability and environmental friendliness. Zn2+‐modified Al2O3/carbonates membranes with the enhanced CO2 permeability have been developed in this work. Interfaces of LiAlO2 were formed on the surface of Al2O3 due to the carbonates incorporation. Microstructural and interfacial characterisation of the membrane revealed that the outermost LiAlO2 layer was due to the reactions between Li2CO3 and ZnAl2O4, resulting in the dissolution of ZnO in the molten carbonate. CO2 permeability of 0.5% ZnAl2O4/Al2O3/carbonates reached 9.12 × 10−12 mol.m−1s−1 Pa−1 at 700°C, higher than that of Al2O3/carbonates, because of the dissolved ZnO. With the increase of ZnAl2O4, CO2 permeability was decreased. The dissolved ZnO in the molten carbonates could enhance the ionic conductivity, whereas a higher amount of ZnO than its solubility will attenuate its effects on CO2 permeation.