Effect of water vapor on deuterium separation by a polymer electrolyte fuel cell

Abstract

Hydrogen isotopes are a valuable source of hydrogen energy through fusion reactions. The materials used in polymer electrolyte fuel cells (PEFCs), such as the hydrophobic support and Pt catalyst, are essentially the same to those used in the conventional isotope-separation method by water–hydrogen chemical exchange. Here, deuterium (D) separation was performed with a PEFC. A gas mixture of H2 and D2 was supplied while changing the humidity. The hydrogen gas and water vapor from the PEFC were analyzed to investigate the D mass balance. Without power generation, D was separated into the water vapor. This can be explained by the vapor-phase catalytic exchange reaction occurring on the platinum catalyst. The fuel-cell reaction enhanced D separation. A large amount of D (approximately 45%) was transferred to the water vapor during power generation. The present results demonstrate the synergistic effect of vapor-phase catalytic exchange and the PEFC on D separation.