Efficiency of hydrogen recovery from reformate with a polymer electrolyte hydrogen pump

The energy efficiency of hydrogen recovery from mixtures of CO₂, H₂O, and H₂ by a polymer electrolyte hydrogen pump (PEHP) has been evaluated. The PEHP pumps protons across the polymer electrolyte, producing >99.99% pure H₂ and a concentrated CO₂ stream. Single stage PEHP experiments recovered 65% of the hydrogen with an energy efficiency of 50%. The energy efficiency is limited by hydrogen mass transport across the porous gas diffusion electrode. The mass transport resistance for hydrogen increases as H₂ is depleted from the CO₂/H₂ mixture by the PEHP. Analysis shows that a multistage PEHP with fixed applied potential difference can recover >90% of the hydrogen with an energy efficiency of 75%, whereas a novel multistage PEHP design with a programmed voltage profile can achieve >90% energy efficiency with >98% hydrogen recovery.