Reducing
the cost of hydrogen transport is an important priority
for the proliferation of clean hydrogen to decarbonize the economy.
It is possible to alleviate the hydrogen transportation costs by delivering
them via existing natural gas pipeline infrastructure. This strategy,
however, necessitates the dilution of hydrogen by blending it with
natural gas as hydrogen embrittlement pipeline materials. In this
work, we deploy high-temperature polymer electrolyte membrane electrochemical
hydrogen pumps (HT-PEM EHPs) to purify hydrogen from dilute hydrogen–natural
gas mixtures (5 to 20 vol % hydrogen). Interestingly, we observe that
activation overpotentials govern HT-PEM EHP polarization when feeding
dilute hydrogen mixtures. Pressurizing the anode to 1.76 barabs enables us to ameliorate interfacial mass transfer resistance and
achieve an EHP limiting current density of 1.4 A cm–2 with a 10 vol % of hydrogen in a natural gas feed. The HT-PEM EHP
showed a small degradation rate, 44 μV h–1, during a 100 h durability test.