Enhancing oxidation stability of amine-containing CO2 adsorbents using hydroxyethyl starch

Amine-based adsorbents are widely used for CO2 capture. However, one of the biggest hurdles for their further development is their limited oxidation stability. Moreover, methods developed to improve the oxidation stability often lead to significant decrease in their CO2 uptake. Here, we investigated the effect of hydroxyethyl starch (HES) on the CO2 uptake and oxidation stability of impregnated polyethylenimine (PEI) adsorbents. Performance of HES-PEI co-impregnated materials was evaluated under different oxidation conditions using CO2 uptake measurements, and mass spectrometry. The effect of HES was compared with other hydroxyl-containing additives such as PVA and PEG, as well as to epoxide functionalization of PEI (EB-PEI). The oxidation stability of PEI upon addition of HES was found to be comparable to EB-PEI containing adsorbent; however, its CO2 uptake, based on PEI, was twice as high. In addition, oxidation stability of supported HES-PEI was significantly higher than unmodified PEI as well as PVA-PEI and PEG-PEI co-impregnated adsorbents.