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Titel:
Hydrogen membrane reactor for industrial hydrogen production and power generation
 
Auteur(s):
 
Gepubliceerd door: Publicatie datum:
ECN Energie Efficiency in de Industrie 1-9-2005
 
ECN publicatienummer: Publicatie type:
ECN-RX--05-154 Conferentiebijdrage
 
Aantal pagina's: Volledige tekst:
12 Download PDF  (699kB)

Gepresenteerd op: 7th International Conference on Catalysis in Membrane Reactors, Cetraro, Italy, 11-14 september 2005.

Samenvatting:

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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