A layered perovskite La2Ni1-xSbxO4+δ-molten carbonate dual-phase membrane for CO2 separation

Abstract

A new series of layered perovskite K2NiF4 structure La2Ni1-xSbxO4+δ (LNSx, x = 0, 0.025, 0.05) were used to prepare the LNSx-molten carbonate (MC) dual-phase membrane for CO2 separation. Sb doping at the Ni site is expected to enhance CO2 permeability and improve the resistance towards CO2/carbonate corrosion. In this work, the CO2 permeability of the LNSx- MC membrane was investigated for CO2-containing atmospheres with and without oxygen, and correlated with the lattice characteristics, microstructure, chemical bond, and conductivity of LNSx support. The result shows that the introduction of Sb improves the structure symmetry and increases the interstitial oxygen concentration, which is beneficial for oxygen ion transport. The superior CO2 permeability of Sb-doped sample is confirmed by the higher permeation fluxes with value of 0.15 mL min−1 cm−2 at 800 °C of LNS0.025-MC dual-phase membrane in 50% CO2 + 50% N2. In addition, the LNS0.025-MC dual-phase membrane achieves a great enhancement in chemical and structural stability compared to the LNS0. In the simulated flue gas 15% CO2 + 10% O2 + 75% N2, the LNS0.05-based dual phase membrane shows a high permeation flux of 1.07 mL min−1 cm−2 at 800 °C, which is 2 times higher than that of LNS0-based dual-phase membrane.