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| Home > Publications database > Development of asymmetric dual phase composite oxygen transport membranes |
| Conference Presentation (After Call) | FZJ-2017-06540 |
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2017
Abstract: DEVELOPMENT OF ASYMMETRIC DUAL PHASE COMPOSITE OXYGEN TRANSPORT MEMBRANESFalk Schulze-Küppers 1 – Stefan Baumann 1 – Madhumidha Ramasamy 1– Wilhelm A. Meulenberg 11 Forschungszentrum Jülich, Institute of Energy and Climate Research, D-52425 Juelich, Germany, e-mail: f.schulze@fz-juelich.deKeywords: Oxygen Transport Membrane, Cer-Cer Dual Phase, asymmetric Membrane, Tape castingMixed Ionic electronic conductors (MIEC) are potential candidates for various applications including oxygen transport membranes (OTM) due to their high efficiency and infinite selectivity towards oxygen at elevated temperatures [1]. Possible applications for OTM are supply of highly pure oxygen or membrane reactors, in which the separated oxygen is directly utilized to form valuable products such as synthetic fuels or bulk chemicals. OTM transport oxygen ions by solid state diffusion through oxygen vacancies, which cannot be occupied by other ions. However, the transport is based on lattice defects and, thus, high-performance OTM materials mainly perovskites (with high defect density and mobility) suffer from limited stability in application conditions with potentially reducing and/or acidic gas atmospheres (requiring low defect density and mobility). One approach to face the trade-off between chemical stability and oxygen flux performance are dual phase composites. In such cer-cer composites two phases are coupled to provide pure electronic and ionic conducting pathway, respectively. In this work, composites of 20 mol% Gadolinia doped ceria (GDC) as ionic conductor and FeCo2O4 spinel (FCO) as electronic conductor are investigated [2]. GDC-FCO ratio is varied proving that spinel content as low as 10 wt-% is sufficient to ensure oxygen permeability, although well below the percolation threshold. In addition, the influence of the powder synthesis route on microstructure and corresponding oxygen permeation properties is investigated and compared to state-of-the-art single phase material, i.e. La0.58Sr0.4Co0.2Fe0.8O3-δ (LSCF). In order to increase oxygen flux further, by microstructural optimization of the membrane layout, asymmetric membranes were manufactured by sequential tape casting. Such membranes consist of a thin (~15 µm), dense membrane layer and a porous support porosity (>40 %) for mechanical stability. An important issue in tape casting is the used raw materials. In order to realize cost efficient manufacturing, a reactive sintering of the membranes was developed, using commercially available CGO, Fe- and Co-oxides as raw material. Oxygen flux in such membranes is clearly limited by surface exchange, due to the low electrochemically active triple phase boundary length, at which oxygen exchange takes place. The performances of bulk and asymmetric membranes are analysed and the potential of this type of materials is discussed with regard to microstructural optimization.References1. J. Sunarso, et. al. “Mixed ionic–electronic conducting (MIEC) ceramic-based membranes for oxygen separation”, J. Mem. Sci., 320, pp.13-41, 20082. M. Ramasamy, et al. “Influence of Microstructure and Surface Activation of Dual-Phase Membrane Ce0.8Gd0.2O2 - FeCo2O4 on Oxygen Permeation” J. Am. Ceram. Soc., 99, pp.349–355, 2016
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