Deep removal of SO2 from cathode air over polyethylenimine-modified SBA-15 sorbents for fuel cells

Abstract

The performance and longevity of fuel cells can be significantly degraded by the contaminants in the air, such as SO2 and NO2, which poison the cathode catalysts. The cleanup of the cathode air in a real environment may thus be required. In this work, SO2 sorption and desorption behavior over molecular basket sorbents (MBSs) consisting of polyethylenimine (PEI) and SBA-15 has been studied. The effects of temperature, PEI loading and SO2 concentration on the sorption capacity of PEI-SBA-15 sorbents were examined. The results showed that the sorption temperature and PEI loading amount greatly influence the sorption performance. The regenerability study showed that only about 10–40 % of sorption capacity was recoverable over the spent PEI-SBA-15 sorbents due to the strong chemical interaction between SO2 and amine sites. Additionally, the influence of co-existing NO2 on SO2 sorption was examined, showing a competitive sorption between SO2 and NO2 over PEI-SBA-15 sorbent. The current study demonstrates that the PEI-BA-15 sorbent could be promising for deep removal of SO2 and NO2 from the cathode air for fuel cells.