DEMOYS

Dense membranes for efficient oxygen and hydrogen separation

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 Obiettivo del progetto (Objective)

'Membranes for oxygen and hydrogen separation play a key-role in the development of CO2 emission-free coal or natural gas power plants. In addition, cost-effective oxygen and hydrogen production processes are urgently needed in gas supply industry. Today existing membranes, however, are not able to meet the requirements for an economical use because of the high costs in combination with limited permeability values and long-term stability in the operating environment. The objective of this project is, therefore, the development of thin mixed conducting membranes for O2 and H2 separation by using a new deposition technique “Low Pressure Plasma Spraying – Thin Film” (LPPS-TF) in combination with nanoporous, highly catalytic layers. TF-LPPS is a technique based on a combination of thermal spray and Physical Vapour Deposition technology. It allows the cost-effective production of thin, dense coatings on large areas at low substrate temperatures and has already successfully been used for the deposition of membranes for the solid oxide fuel cells. In this project both ceramic and metallic substrates will be used for deposition. It is expected that, by using the LPPS-TF process a dense, stable deposit with thickness lower than 20 micron can be obtained. This would allow to increase membrane performances while decreasing their manufacturing costs. Catalytic layers will be also applied to enhance the surface reactions becoming rate limiting for thin membranes. Membrane performances will be assessed in pilot loops in order to meet specific targets in terms of permeability and stability at temperature. A modelling study concerning the integration of the developed membranes in power and hydrogen production plants will be also performed. This will provide inputs for process scale-up and cost evaluation in the selected plant configurations in order to approach zero CO2 emission and a CO2 capture cost of 15 €/ton.'

Introduzione (Teaser)

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.

Descrizione progetto (Article)

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 http://demoys.rse-web.it/ (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.