High-temperature CO2 perm-selectivity of yttrium-doped SDC ceramic–carbonate dual-phase membranes

Abstract

This work presents the synthesis and evaluation of ceramic supports made of yttrium and samarium co-doped CeO₂ (Y-SDC) for synthesizing ceramic–carbonate dual-phase membranes. Their Y : Sm atomic concentration ratio was varied, using a total dopant content of 20 mol%. The Y-SDC supports were characterized by X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and electrical conductivity under different atmospheres, for determining the chemical and thermal stability and the intrinsic properties of the ceramic supports. The supports were infiltrated with molten carbonates for making dense dual-phase membranes, and CO₂ permeation tests were conducted using a feed gas mixture of CO₂/N₂ between 700 and 900 °C at 1 bar. This study establishes that Y-SDC supports are thermally and chemically stable at high temperatures in acid environments. The ionic conductivity of Y-SDC depends on the O₂ partial pressure and yttrium content. The CO₂ permeation flux results of the dense ceramic–carbonate dual-phase membrane are correlated to the ionic conductivity of Y-SDC. Moreover, the CO₂ permeation is improved by tailoring the membrane microstructure.