Effect of natural gas impurities on electrochemical hydrogen compression and strategies for mitigation

Admixing of H 2 into the natural gas grid is a viable option for mid-term transportation. Electrochemical H 2 compressors (EHCs) separate H 2 from methane but are prone to poisoning due to impurities. This study compares low- and high-temperature EHCs regarding their tolerance towards natural gas impurities, focusing on the underexplored contaminants NH 3 and H 2 S and mitigation strategies. The impact of impurities was evaluated using 5 h chronopotentiometry, cyclic voltammetry, and electrochemical impedance spectroscopy. Low-temperature EHC (70 °C) showed an increase of up to 200 % in cell potential, while the increase remained below 6 % for high-temperature EHC (120 °C), when operated with CO 2 , CO, or H 2 S . When diluting the H 2 / H 2 S mixture in the high-temperature EHC with CH 4 , oscillations and an increase in cell potential were observed, which was mitigated when operating at 160 °C or via electro-oxidation. The results establish a foundation for long-term stability testing in natural gas. • Comparison of low- and high-temperature electrochemical hydrogen compression (EHC). • Natural gas impurities effect (NH 3 , CO 2 , CO, H 2 S) on EHC. • 200 % cell potential increase in low-temperature EHC when operating with 3.5 ppm H 2 S. • Potential oscillations in high-temperature EHC with diluted H 2 S in H 2 . • Repeated cyclic oxidation mitigates H 2 S poisoning in high-temperature EHC.