Prediction of Hydrogen Flux Through Sulfur-Tolerant Binary Alloy Membranes
Preeti Kamakoti,1,2
Bryan D. Morreale,1
Michael V. Ciocco,1
Bret H. Howard,1
Richard P. Killmeyer,1
Anthony V. Cugini,1
David S. Sholl2*
Metal membranes play a vital role in hydrogen purification.
Defect-free membranes can exhibit effectively infinite selectivity
but must also provide high fluxes, resistance to poisoning,
long operational lifetimes, and low cost. Alloying offers one
route to improve on membranes based on pure metals such as palladium.
We show how ab initio calculations and coarse-grained modeling
can accurately predict hydrogen fluxes through binary alloy
membranes as functions of alloy composition, temperature, and
pressure. Our approach, which requires no experimental input
apart from knowledge of bulk crystal structures, is demonstrated
for palladium-copper alloys, which show nontrivial behavior
due to the existence of face-centered cubic and body-centered
cubic crystal structures and have the potential to resist sulfur
poisoning. The accuracy of our approach is examined by a comparison
with extensive experiments using thick foils at elevated temperatures.
Our experiments also demonstrate the ability of these membranes
to resist poisoning by hydrogen sulfide.
2 Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
* To whom correspondence should be addressed. E-mail: sholl{at}andrew.cmu.edu
