To produce high purity hydrogen fuel from coal, hydrogen gas has to be extracted from synthesis gas (syngas), a product of coal gasification. Using gas separation membranes is one way to achieve this goal. Although a variety of hydrogen separation membrane materials exist today, none of them are shown to be suitable for employment in contaminant-laden syngas at elevated temperatures.

Surface poisoning and corrosion are shown to be the most significant degradation mechanisms acting on the hydrogen membrane materials at elevated temperatures in synthesis gas derived from coal. Among other metallic dense membrane materials, copper-palladium alloys have demonstrated promise for being resistant against these degradation mechanisms.

NETL materials researchers discovered that the addition of magnesium extends the elevated-temperature structural stability of materials showing promise for separating hydrogen from coal-derived syngas. The copper-palladium-magnesium formulation maintains its more open body-centered cubic crystal structure, which is associated with high hydrogen flux, at significantly higher temperature than copper-palladium alloys.

The researchers predicted magnesium would have this stabilizing potential from first principles density functional theory calculations. A microstructural characterization of the newly developed hydrogen separation membrane alloy has been published in Elsevier’s Journal of Alloys and Compounds, Vol. 528 (2012), pp. 10-15.

This research was performed in support of NETL’s Fuels Program of the Strategic Center for Coal.

Contacts: Ömer Doğan, 541-967-5858 and Michael Gao, 541-967-5869