Development of novel sorbents for removing SO₂ from cathode air for fuel cells

Nowadays, fuel cells have been considered as a promising device for portable power supply. Almost all fuel cells use air as an oxidant. However, there are many contaminants in the air that may significantly degrade the performance of the fuel cells. Although researchers have realized the significant effect of the contaminants in cathode air on the fuel cell performance, little or no work has been reported on the cleanup of cathode air for fuel cells. In the present paper, we report two novel types of "Molecular Basket" sorbents, PEG(50)/SBA-15 and PEI(50)/SBA-15, for SO2 removal at room temperature. Both sorbents could effectively remove SO2 to at least lower than 0.2 ppmv. It was found that the spent PEG(50)/SBA-15 can be regenerated and the capacity can be completely recovered. Although the sorption capacity of PEI(50)/SBA-15 can be only partly recovered (about one-tenth), the initial capacity for SO2 sorption can reach as high as 136 mg-SO2/g, the highest one ever reported in open literature to the best of our knowledge. Both sorbents are promising for SO2 removal and cleanup of cathode air for fuel cells.