(288d) Microstructured Palladium-Based Membranes for Hydrogen Purification

Zachary W. Dunbar and Deryn Chu

Abstract:

Portable fuel cells have potential to fill a unique power
niche in the US Army for small to intermediate power demands, such as battery
charging, drone power, small gensets, and auxillary power units. 
Mobile fuel reformation is sought by the Army to provide mobile
hydrogen-on-demand for fuel cell applications, using logistic fuels as a
hydrogen carrier.  Unfortunately, running
a fuel cell on pure logistic fuels reformate is troublesome, due to its high
concentrations of carbon monoxide, hydrogen sulfide, and coking
precursors. 

To alleviate this issue, a purification step is necessary to
clean up the gas stream being processed by the fuel cell.  Palladium based membrane technology is an
ideal candidate for this operation.

In this work, microfabrication processes are used to
engineer a microstructured metallic support for both pure palladium and
palladium-copper alloy membranes.  The
resulting membranes are entirely metallic, and have planar geometry.  The active layer for hydrogen purification is
varied between 250 and 500 nanometers, while the nickel mechanical support is
approximately 10 microns in thickness. 
The membranes are tested under pure hydrogen and synthetic water gas
shift atmospheres.  Hydrogen flux,
selectivity, hydrogen sulfide sensitivity and long term durability are
evaluated.