Branched versus Linear Structure: Lowering the CO2 Desorption Temperature of Polyethylenimine-Functionalized Silica Adsorbents

Lowering the regeneration temperature for solid CO2-capture materials is one of critical tasks economizing CO2-capturing processes. Based on reported pKa values and nucleophilicity, we compared two different polyethylenimines (PEIs): branched PEI (BPEI) linear (LPEI). LPEI outperformed BPEI in terms adsorption desorption properties. Because a below 73–75 °C, even high loading amount can effectively adsorb CO2 without diffusive barriers. Temperature-programmed (TPD) demonstrated that peak top dropped to 50.8 °C LPEI, 78.0 BPEI. We also revisited classical model secondary amines by using situ modulation excitation IR spectroscopy, proposed new configuration, R1(R2)-NCOOH. Even though more expensive than BPEI, considering long-term operation system, low makes attractive industrial applications.