A novel multilayer metal membrane has been developed that can be used
for the separation of ultra-high purity hydrogen from impure feed stre
ams. The membrane is comprised of very thin layers of dense palladium
film deposited on both sides of a thin Group V metal foil, ion-mined p
rior to the deposition of the palladium. This membrane operates at ele
vated temperatures on the order of 300 degrees C and is capable of hig
h rates of hydrogen flow. Flows are dependent on the pressure differen
tial applied to the membrane, but flows of 100 standard cubic centimet
ers of hydrogen per minute per square centimeter of membrane and highe
r are regularly observed with differentials of under one atmosphere. T
esting of the membrane for a period of 775 h showed stable flows under
constant conditions. A membrane system has been successfully applied
to a proton exchange membrane fuel cell and was tested using a pseudo-
reformate feed stream containing 1% carbon monoxide without any degrad
ation in performance. (C) 1997 International Association for Hydrogen
Energy.