Purifying Hydrogen from Dilute Hydrogen–Natural Gas Mixtures Using HT-PEM Electrochemical Hydrogen Pumps

Abstract

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.