Some anion-transport properties of Nafion~(TM) 117 from fuel cell hydrogen peroxide generation data

摘要

Hydrogen peroxide generation R&D data obtained in an alkaline fuel cell-type electrochemical reactor with a dividing Nation~(TM) 117 membrane have been used to extract anion-conducting properties of the cation-exchange membrane. The effective diffusion coefficient of NaOH and the average transport number of OH~(-) in the membrane were obtained by fitting a model formula for the total alkalinity of outlet catholyte to experimental alkalinities obtained with various electrolysis parameters' values. The formula resulted from assumptions that NaOH diffuses through the membrane and OH~- migrates through the membrane, and that HO_2~- does not penetrate the membrane. The membrane parameters extracted in this way were in good agreement with similar data reported by others for Nafion~(TM). Hydrogen peroxide current efficiencies remained over 90 percent and H_2O_2 concentrations reached 7 wt. percent, however the fuel cell reactor's electrical efficiency was strongly limited by high internal resistance.