CO2 permeation through asymmetric thin tubular ceramic-carbonate dual-phase membranes

Abstract Ceramic-carbonate dual-phase dense membrane is a promising high temperature CO 2 separation membrane with remarkable CO 2 permeance and theoretically infinite CO 2 selectivity. This paper reports synthesis and CO 2 permeation properties of asymmetric tubular dual-phase membranes with a thin samarium doped ceria (Ce 0.8 Sm 0.2 O 1.9 , SDC)-carbonate separation layer and a thick porous SDC-Bi 1.5 Y 0.3 Sm 0.2 O 3-δ (BYS) support. The asymmetric tubular thin (0.12 mm) dual-phase membrane has much higher CO 2 permeance and lower activation energy for permeation than the thick (1.0–1.5 mm) membranes. At 900 °C with 50%CO 2 /N 2 feed at 1 atm, the CO 2 permeation flux and permeance for the thin membrane reach 1.53 × 10 −2 mol m −2 s −1 (or 2.05 mL(STP) cm −2 min −1 ) and 3.16 × 10 −7 mol m −2 s −1 Pa −1 , respectively, with activation energy for permeation of 62.5 kJ/mol. These dual-phase membranes exhibit slightly higher CO 2 permeance with essentially same activation energy for permeation, and stable operation, for CO 2 permeation with simulated syngas (with the composition of 49.5%CO, 36%CO 2 , 4.5%N 2 , 10%H 2 ) feed. The CO 2 permeation fluxes of the tubular asymmetric membranes can be well described by the power-function flux equation. The analysis of CO 2 permeation data with the model shows that the CO 2 separation performance of the tubular asymmetric membranes can be further improved by optimizing the microstructure of ceramic porous supports. This work demonstrates that asymmetric SDC-carbonate dual-phase membrane has high potential for practical application in high temperature CO 2 separation.