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Title:
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Hydrogen membrane reactor for industrial hydrogen production and power generation
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Author(s):
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Published by:
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Publication date:
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ECN
Energy Efficiency in Industry
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1-9-2005
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ECN report number:
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Document type:
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ECN-RX--05-154
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Conference Paper
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Number of pages:
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Full text:
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12
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Download PDF
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Presented at: 7th International Conference on Catalysis in Membrane Reactors, Cetraro, Italy, 11-14 september 2005.
Abstract:
Combiningreaction and separation using membrane reactors has shown to offer numerous
advantages for hydrogen production in future power production systems
and industrial chemical production processes. The application of hydrogen
selective membranes for the removal of hydrogen from reforming and shift
reactions gives higher conversion of these equilibrium reactions at
lower temperatures while elegantly CO2 can be captured under
high pressure or chemical products can be obtained cost-effectively.
In steam reforming and water gas shift processes membrane separation
can be economical viable using current thin layer palladium alloy membrane
technology, however a further increase in flux and/or decrease in membrane
price is absolutely needed to convince the process owners of the suitability
of this promising technology. Also a customized catalyst is required
for reforming of methane, which should be active at low temperatures
and resistant to coke formation under the carbon-rich membrane conditions.
This paper gives an overview of the results and current status of the
hydrogen membrane reactor development at ECN for energy efficient industrial hydrogen production and power generation.
Dense tubular membranes with very thin Pd/Ag layers have been
made on ceramic supports with electroless plating on a 1m2
scale. The membranes have been used for single gas permeance tests at
different temperatures and for the separation of hydrogen from reformate
gas, using a bench scale test system that can operate up to 500ºC and
65bar feed pressure with a membrane area of about 50cm2.
Hydrogen permeation measurements have shown that after initial activation
very high hydrogen permeances of 50-100m3/m2hbar0.5
can be obtained with high permselectivities. Tests with simulated reformate
gas at 500ºC gave lower selectivities due to lower hydrogen permeances
caused by the poisonous CO in the reformate gas. With the Pd/Ag membrane
the hydrogen concentration was increased from 10% in the simulated reformate
gas to 90% in the permeate. A shift in equilibrium was observed and
extra hydrogen was produced without the use of a catalyst. Prior to
actually testing the performance of the membrane reactor, different
catalysts have been tested under simulated membrane reactor gas conditions.
During 140h on stream at 500°C, the reference nickel catalyst showed
significant deactivation under the simulated membrane reactor conditions,
probably due to carbon deposition. The noble catalyst did not show significant
deactivation and was selected for application in the membrane reactor.
It was shown that methane conversions well beyond the thermodynamic
limits could be reached during steam reforming at 500-600°C and 50 bar
in the membrane reactor. The membrane has been on stream for more than
100 days using different feed gases and is showing acceptable performance.
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