Development of Thin Film Oxygen Transport Membranes on Metallic Supports
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Beschreibung
Asymmetric membrane structure has an attractive potential in the application of O2/N2 gas
separation membrane for the future membrane-based fossil fuel power plant using oxyfuel
technology, which will reduce the carbon dioxide emission. The aim of this study is the
development of a metal supported multi-layer membrane structure with a thin film top
membrane layer and porous ceramic interlayers.
Four perovskite materials were studied as candidate membrane materials. Material
properties of these perovskite materials were investigated and compared.
La0.58Sr0.4Co0.2Fe0.8O3- (LSCF58428) showed sufficient oxygen permeability, an
acceptable thermal expansion coefficient and a moderate sintering temperature.
Alternatively, Ba0.5Sr0.5Co0.8Fe0.2O3- (BSCF5582) is considered obtaining very high
oxygen permeability but a higher thermal expansion and a lower thermal stability than
LSCF58428.
Four different Ni-based alloys were studied as candidate substrate materials in the
asymmetric membrane structure. The chromia-scale alloys (Hastelloy X, Inconel 600 and
Haynes 214) caused Cr poisoning of the membrane layer material LSCF58428 during
high-temperature co-firing in air. NiCoCrAlY with a high Al content (12.7 wt%) was
found to be the most promising substrate material. It showed a good chemical
compatibility with perovskite materials at high temperatures.
In order to bridge the highly porous substrate and the thin top membrane layer interlayers
were developed. Two interlayers were coated by screen printing on the porous
NiCoCrAlY substrate which was sintered at 1225°C in flowing H2 atmosphere. Screen
printing pastes were optimized by investigating various solvent and binder combinations
and various ceramic powder contents. The first interlayer significantly improved the
surface quality and the surface pore size has been reduced from 30-50μm on the substrate
to few μm on the first interlayer, though it comprised some cracks. The second interlayer
had a crack-free and porous structure. The top membrane layer was deposited by physical
vapor deposition (magnetron sputtering) with a thickness of 3.8 μm improving the gastightness
considerably but showing still reasonable air-leakage. Summarizing, the
successful development of a metal-perovskite-composite could be shown, which acts as a
basis for a further development of a gas-tight metal supported oxygen transport
asymmetric membrane structure
Autor*in
Ye Xing
Themen in »Development of Thin Film Oxygen Transport Membranes on Metallic Supports«
Materials PVD Perovskite materials