TY - JOUR

T1 - Ca-containing CO2-tolerant perovskite materials for oxygen separation

AU - Efimov, Konstantin

AU - Klande, Tobias

AU - Juditzki, Nadine

AU - Feldhoff, Armin

N1 - Funding Information: The authors acknowledge financial support from the State of Lower Saxony (Germany, NTH bottom-up project, no. 21-71023-25-7/09 ).

PY - 2012/2/1

Y1 - 2012/2/1

N2 - Perovskites (La 1-xCa x)FeO 3-δ and (La 1-xCa x)(Co 0.8Fe 0.2)O 3-δ with varying La and Ca contents (x=0.4-0.6) were designed by sol-gel route as model membrane materials to be an alternative to Ba- and Sr-based systems for operation in the presence of CO 2. It was found that only the first members of the systems with x=0.4 consisted of almost pure perovskite phases. The materials containing more Ca (x=0.5-0.6) exhibited a considerable amount of bi-phase material, such as brownmillerite and/or spinel, after calcination at 1223K. The orthorhombicly distorted (La 0.6Ca 0.4)FeO 3-δ and rhombohedrally distorted (La 0.6Ca 0.4)(Co 0.8Fe 0.2)O 3-δ perovskites showed relatively high oxygen permeation fluxes at 1223K of 0.26cm 3min -1cm -2 and 0.43cm 3min -1cm -2, respectively. The oxygen-ionic conductivity of the materials was improved by about 50% via an asymmetric configuration using a porous support and an approximately 10-μm thick dense layer with the same chemical composition. In situ XRD in an atmosphere containing 50vol.% CO 2 and long-term oxygen permeation experiments using pure CO 2 as the sweep gas revealed a high tolerance of Ca-based materials toward CO 2. Thus, we suggest that Ca-containing perovskite can be considered promising membrane materials if operation in the presence of CO 2 is required.

AB - Perovskites (La 1-xCa x)FeO 3-δ and (La 1-xCa x)(Co 0.8Fe 0.2)O 3-δ with varying La and Ca contents (x=0.4-0.6) were designed by sol-gel route as model membrane materials to be an alternative to Ba- and Sr-based systems for operation in the presence of CO 2. It was found that only the first members of the systems with x=0.4 consisted of almost pure perovskite phases. The materials containing more Ca (x=0.5-0.6) exhibited a considerable amount of bi-phase material, such as brownmillerite and/or spinel, after calcination at 1223K. The orthorhombicly distorted (La 0.6Ca 0.4)FeO 3-δ and rhombohedrally distorted (La 0.6Ca 0.4)(Co 0.8Fe 0.2)O 3-δ perovskites showed relatively high oxygen permeation fluxes at 1223K of 0.26cm 3min -1cm -2 and 0.43cm 3min -1cm -2, respectively. The oxygen-ionic conductivity of the materials was improved by about 50% via an asymmetric configuration using a porous support and an approximately 10-μm thick dense layer with the same chemical composition. In situ XRD in an atmosphere containing 50vol.% CO 2 and long-term oxygen permeation experiments using pure CO 2 as the sweep gas revealed a high tolerance of Ca-based materials toward CO 2. Thus, we suggest that Ca-containing perovskite can be considered promising membrane materials if operation in the presence of CO 2 is required.

KW - Asymmetric membrane

KW - In-situ X-ray diffraction

KW - Mixed ionic-electronic conductor

KW - Perovskite, CO -stability

KW - Transmission electron microscopy

UR - http://www.scopus.com/inward/record.url?scp=83855163560&partnerID=8YFLogxK

U2 - 10.1016/j.memsci.2011.10.030

DO - 10.1016/j.memsci.2011.10.030

M3 - Article

AN - SCOPUS:83855163560

VL - 389

SP - 205

EP - 215

JO - Journal of membrane science

JF - Journal of membrane science

SN - 0376-7388

ER -