In-situ IR Study on Stability of Epoxide-Functionalized Polyethyleneimine CO₂ Adsorbent to NO₂ and SO₂ Gases

This study investigates the stability of amine-impregnated CO₂ adsorbents, specifically polyethyleneimine (PEI) and epoxybutane-modified PEI (EB-PEI), when exposed to acidic gases like SO₂ and NO₂. Using in-situ FT-IR spectroscopy, the formation of degradation products such as nitro groups, NH₂–SO₂, NH₂–NO₂ complexes, and amides was identified. These degradation species were observed to form more rapidly at higher temperatures, with NO₂ causing more significant oxidation compared to SO₂. The study evaluated the impact of acid gas exposure on CO₂ adsorption performance, revealing that higher concentrations of acidic gases led to a substantial decrease in adsorption capacity. SO₂ had a more detrimental effect on the CO₂ adsorption capacity than NO₂, and EB-PEI exhibited greater resistance to SO₂ due to its higher proportion of secondary amines.