Role of Fe/Co Ratio in Dual Phase Ce0.8Gd0.2O2−δ–Fe3−xCoxO4 Composites for Oxygen Separation

Membranes, vol. 13, pp. 482

Abstract

Dual-phase membranes are increasingly attracting attention as a solution for developing stable oxygen permeation membranes. Ce0.8Gd0.2O2−δ–Fe3−xCoxO4 (CGO-F(3−x)CxO) composites are one group of promising candidates. This study aims to understand the effect of the Fe/Co-ratio, i.e., x = 0, 1, 2, and 3 in Fe3−xCoxO4, on microstructure evolution and performance of the composite. The samples were prepared using the solid-state reactive sintering method (SSRS) to induce phase interactions, which determines the final composite microstructure. The Fe/Co ratio in the spinel structure was found to be a crucial factor in determining phase evolution, microstructure, and permeation of the material. Microstructure analysis showed that all iron-free composites had a dual-phase structure after sintering. In contrast, iron-containing composites formed additional phases with a spinel or garnet structure which likely contributed to electronic conductivity. The presence of both cations resulted in better performance than that of pure iron or cobalt oxides. This demonstrated that both types of cations were necessary to form a composite structure, which then allowed sufficient percolation of robust electronic and ionic conducting pathways. The maximum oxygen flux is jO2 = 0.16 and 0.11 mL/cm2·s at 1000 °C and 850 °C, respectively, of the 85CGO-FC2O composite, which is comparable oxygen permeation flux reported previously.

Authors 10

1. Liudmila Fischer corresponding

   Forschungszentrum Jülich · University of Twente

   Affiliation as printed

   Faculty of Science and Technology, Inorganic Membranes, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands

   Institute of Energy and Climate Research IEK-1, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany

2. Ke Ran Aachen Central Facility for Electron Microscopy GFE

   RWTH Aachen University · Forschungszentrum Jülich · Ernst Ruska Centre

   Affiliation as printed

   Central Facility for Electron Microscopy GFE, RWTH Aachen University, 52074 Aachen, Germany

   Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons ER-C, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany

3. Christina Schmidt

   Forschungszentrum Jülich · Helmholtz-Institute Münster

   Affiliation as printed

   Institute of Energy and Climate Research IEK-12, Forschungszentrum Jülich GmbH Helmholtz-Institute Münster, 48149 Münster, Germany

4. Kerstin Neuhaus

   Forschungszentrum Jülich · Helmholtz-Institute Münster

   Affiliation as printed

   Institute of Energy and Climate Research IEK-12, Forschungszentrum Jülich GmbH Helmholtz-Institute Münster, 48149 Münster, Germany

5. Stefan Baumann corresponding

   Forschungszentrum Jülich

   Affiliation as printed

   Institute of Energy and Climate Research IEK-1, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany

6. Joachim Mayer Aachen Central Facility for Electron Microscopy GFE

   RWTH Aachen University · Forschungszentrum Jülich · Ernst Ruska Centre

   Affiliation as printed

   Central Facility for Electron Microscopy GFE, RWTH Aachen University, 52074 Aachen, Germany

   Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons ER-C, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany

7. Henny J. M. Bouwmeester

   University of Twente

   Affiliation as printed

   Faculty of Science and Technology, Inorganic Membranes, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands

8. Arian Nijmeijer

   University of Twente

   Affiliation as printed

   Faculty of Science and Technology, Inorganic Membranes, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands

9. Olivier Guillon

   Forschungszentrum Jülich · Jülich Aachen Research Alliance

   Affiliation as printed

   Institute of Energy and Climate Research IEK-1, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany

   Jülich Aachen Research Allianc JARA-Energy, 52425 Jülich, Germany

10. Wilhelm Albert Meulenberg

    Forschungszentrum Jülich · University of Twente

    Affiliation as printed

    Faculty of Science and Technology, Inorganic Membranes, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands

    Institute of Energy and Climate Research IEK-1, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany