Qualitative determination of H2S crossover rates in nation membranes using ion-probe techniques

Conference · Tue Jan 01 04:00:00 EST 2008

OSTI ID:957791

Brosha, Eric L ^[1]; Rockward, Tommy ^[1]; Uribe, Francisco A ^[1]; Garzon, Fernando H ^[1]

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1. Los Alamos National Laboratory

Polymer electrolyte membrane fuel cells are sensitive to impurities that may be present in either the oxidizer or fuel. H2S, even at the ppb level, will have a dramatic and adverse affect on fuel cell performance. The H2S permeability through dry and humidified Nafion PEMFC membranes was studied using ion probe techniques. A sulfide anti-oxidant buffer solution was used to trap and concentrate trace quantities of H2S that permeated through 50 cm2samples of Nafion 117 and 212 membranes using a partial pressure difference up to I030ppm at room temperature. Experiments were conducted for up to 24 hours in order to achieve sulfide ion concentrations high enough to be precisely determined by subsequent titration with Pb(N03)2. The rate of H2S crossover for dry 117 and 212 were identical at 1.2e-7 g/min. Humidification increased the crossover rate to 5.ge-7 glmin and 1.8e-6 glmin for 117 and 212 respectively. Although the data collected in this work show that the rate of H2S crossover increases with water content and reduced membrane thickness, an accurate determination of permeation constants from this work was not possible because the H2S partial pressure was not constant throughout the experiment.

• Research Organization: Los Alamos National Laboratory (LANL)
• Sponsoring Organization: DOE
• DOE Contract Number: AC52-06NA25396
• OSTI ID: 957791
• Report Number(s): LA-UR-08-04652; LA-UR-08-4652
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BUFFERS
ELECTROLYTES
FUEL CELLS
IMPURITIES
ION PROBES
MEMBRANES
OXIDIZERS
PARTIAL PRESSURE
PERFORMANCE
PERMEABILITY
POLYMERS
SULFIDES
THICKNESS
TITRATION