Thermochemical stability of Fe- and co-functionalized perovskite-type SrTiO3 oxygen transport membrane materials in syngas conditions

• Published in: Journal of the European Ceramic Society 2019-12, Vol.39 (15), p.4874-4881
• Main Authors: Liu, Yang, Motalov, Vladimir, Baumann, Stefan, Sergeev, Dmitry, Müller, Michael, Sohn, Yoo Jung, Guillon, Olivier
• Format: Article
• Language: English
• Subjects: Knudsen effusion mass spectrometry; Oxygen transport membrane; Strontium titanate; Syngas; Thermochemical stability
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2019.06.045

The materials typically used for oxygen transport membranes, Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) and La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) tend to decompose due to their low thermochemical stability under reducing atmosphere. Fe- and Co-doped SrTiO3 (SrTi1-x-yCoxFeyO3-δ, x + y ≤ 0.35) (STCF) materials showing an oxygen transport comparable to LSCF have great potential for application in ion-transport-devices. In this study, the thermochemical stability of pure perovskite-structured STCF was investigated after annealing in a syngas atmosphere at 600–900 °C. The phase composition of the materials after annealing was characterized by means of X-ray diffraction (XRD). The thermodynamic activities of SrO, FeO, and CoO in the STCF materials were evaluated using Knudsen effusion mass spectrometry (KEMS). Co-doped SrTiO3 (STC) materials were not stable after annealing in the syngas atmosphere above 5 mol% Co-substitution. Ruddlesden-Popper-like phases and SrCO3 were detected after annealing at 600 °C. In contrast, Fe substitution (STF) showed good stability after annealing in syngas upto 35 mol% substitution.