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Keywords:

  • hydrogen;
  • reformate purification;
  • electrochemical separations;
  • carbon dioxide removal

Abstract

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. © 2010 American Institute of Chemical Engineers AIChE J, 2011