Evaluation of activated carbon adsorbent for fuel cell cathode air filtration

The effectiveness of a commercial activated carbon modified by KOH (KMAC) was evaluated as adsorbent for purifying NOx and SO2, which are the major contaminants in fuel cell cathode air stream. The N2 adsorption–desorption isotherms of KMAC samples showed that the surface structure of the activated carbon was changed significantly by KOH impregnation. The sample of KMAC with a loading of 10.1% KOH by weight presented the highest adsorption capacities for both NOx and SO2, which were 96 mg g−1 and 255 mg g−1, respectively. A pre-exposure of KMAC to CO2 caused neither effect on the adsorption of NOx nor on the adsorption of SO2. KMAC could fully protect a 250 W proton exchange membrane fuel cell (PEMFC) stack from 1100 ppb of NOx and 250 ppb of SO2 for about 130 h.