Ceramic-carbonate dual-phase membrane with improved chemical stability for carbon dioxide separation at high temperature

This study examines membrane synthesis, structural stability, permeation properties, and long-term permeation stability of a new dense dual-phase membrane of composition La_0.85Ce_0.1Ga_0.3Fe _0.65Al_0.05O_{3 - δ} (LCGFA)-carbonate for high temperature CO₂ separation. Porous ceramic supports made by sintering pressed powder at a temperature below its densification temperature resulted in a desired support with an open porosity ranging between 40 and 50%. The dual-phase membranes was prepared by direct infiltration of the ceramic supports in molten carbonate at 600 °C, resulting in a four order of magnitude decrease in permeance when compared to the support. LCGFA-carbonate membranes are stable when exposed to gases ranging from gas mixtures containing N₂ and various concentrations of CO₂ to simulated syngas, and exhibit a stable long term CO₂ permeation flux of 0.025 mL·min^{- 1}·cm^{- 2} for more than 275 h at 900 °C. The CO₂ permeation results show exponential dependence to increasing system temperature as well as a linear dependence to logarithmic change in CO₂ partial pressure gradients across the membrane in the CO₂ pressure range studied.