Development of a hydrogen purifier with Pd-based composite membrane

A hydrogen purifier equipped with Pd-Cu-Ni/PNS membranes has been developed to purify low-grade hydrogen and supply it to processes requiring high-purity hydrogen. The purifier does not include any purge system to flush out hydrogen from the membrane module to prevent membrane embrittlement because there is no α-β phase transition below the critical point of the Pd-H system, making the purifier simple. The hydrogen purifier was tested with three different grades of hydrogen, 90, 99 and 99.9%, to determine the effects of the grade of feed hydrogen on the hydrogen permeation behavior. A lower grade required a lower recovery ratio of the purifier to obtain a given relative hydrogen permeation flux. It was confirmed that the purifier can provide high-purity hydrogen to a gas chromatograph (GC) for carrier and make-up gases. A 75-day durability test provided evidence that the hydrogen purifier could be useful for extended periods as needed for commercial processes.