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Dense membranes for efficient oxygen and hydrogen separation

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Dense membranes for efficient gas separation

EU-funded scientists employed a new deposition technique for developing thin-mixed conducting membranes for hydrogen and oxygen separation. The deposition process should allow increasing membrane performance, while decreasing manufacturing costs.

Industrial Technologies

Hydrogen and oxygen separation membranes are expected to play an important role in achieving zero carbon dioxide (CO2) emission power generation from coal or natural gas. Moreover, these membranes can potentially find use in power and hydrogen co-production plants. Current technology is limited by separation efficiency, stability over time and costs. Exploitation of a new deposition technique within the context of the EU-funded project DEMOYS (Dense membranes for efficient oxygen and hydrogen separation) enabled scientists to overcome these barriers. Low-pressure plasma-spray thin-film deposition, proprietary technology of a project partner, combines conventional thermal spraying and thin-film technologies. Low-pressure operation facilitates cost-effective fabrication of dense, thin-film coatings on large-area substrates at low temperatures. Scientists used the technology to apply dense, stable coatings leading to membranes with thickness less than 50 micrometres. Catalytic functionalisation enhanced surface reactions, the rate-limiting factor for thin membranes. Scientists used lanthanum strontium cobalt ferrite (LSCF) and lanthanum wolfram oxide (LWO) as reference materials for oxygen and hydrogen separation membranes. Several batches of powders were manufactured and deposited on metallic porous supports, amongst which MCrAlY-alloy proved to be the most suitable for the particular deposition process. The team also produced a nanoporous layer between the support and the dense membrane which increased permeation fluxes and stability. A modelling study concerning the integration of the developed membranes in power and hydrogen plants supported experimental work. The study provided inputs for scaling up the deposition process and evaluating the costs in selected plant configurations to approach zero-carbon emissions and minimise CO2 capture costs. The cost estimate of electricity and CO2 capture focused on oxygen transport membranes in coal-based power plants. Scientists concluded that their integration in power plants with low carbon emissions can prove more cost effective than benchmark plants using the leading CO2 capture technologies. In addition, the use of oxygen transport membranes in oxygen and electric power co-production plants can be more cost effective than benchmark Pressure or Vacuum Swing Adsorption plants. DEMOYS membranes are very promising and can lead to important environmental and economic benefits. Improved efficiency at a lower cost should provide the EU with a competitive advantage.

Keywords

Dense membranes, gas separation, hydrogen and oxygen separation, plasma-spray, thin-film deposition

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