NOVELTY - A hydrogen purification device comprises hydrogen-selective membrane(s) including first surface to be contacted by mixed gas stream and permeate surface. The permeate stream is formed from portion of mixed gas stream that passes through membrane to permeate surface. The membrane is composed of a primary component from palladium or palladium alloy.    USE - For production of purified hydrogen used in the manufacture of metals, edible fats and oils, semiconductors and microelectronics. Purified hydrogen is also an important fuel source for many energy conversion devices, e.g. fuel cells to produce electrical potential.    ADVANTAGE - Prior to delivering the stream to a fuel cell, a stack of fuel cells, or another hydrogen-consuming device, the mixed gas stream may be purified, in order to remove undesirable impurities.    DETAILED DESCRIPTION - A hydrogen purification device (10) comprises an enclosure (12) defining an internal compartment (18) and including at least one input port through which a mixed gas stream (34) containing hydrogen gas (26) and other gases (28) is delivered to the enclosure, at least one product outputting port through which a permeate stream (32) containing at least one pure hydrogen is removed from the enclosure, and at least one byproduct output port through which a byproduct stream (36) containing at least a portion of the other gases is removed from the enclosure. At least one hydrogen-selective membrane (46) is disposed within the compartment. The membrane includes a first surface adapted to be contacted by the mixed gas stream and a permeate surface opposed to the first surface. The permeate stream is formed from the portion of the mixed gas stream that passes through the hydrogen-selective membrane to the permeate surface. The byproduct stream is formed from the portion of the mixed gas stream that does not pass through the membrane. The membrane is composed of a primary component from palladium or palladium alloy. It further comprises a secondary component consisting of approximately 5-100 ppm silicon.    An INDEPENDENT CLAIM is also included for a hydrogen purification device that is adapted to be operated under predetermined conditions.    DESCRIPTION OF DRAWING(S) - The figure is a schematic view of a hydrogen purification device.    Hydrogen purification device (10)    Enclosure (12)    Internal compartment (18)    Hydrogen gas (26)    Other gases (28)    Permeate stream (32)    Mixed gas stream (34)    Byproduct stream (36)    Hydrogen-selective membrane (46)