A moisture swing sorbent for direct air capture of carbon dioxide: Thermodynamic and kinetic analysis

An amine-based anion exchange resin was utilized to capture CO₂ from ambient air. The sorbent is able to absorb CO₂ when it is dry and release CO₂ when exposed to liquid water or water vapor. The absorption isotherm test shows that the sorbent behaves efficiently even at very low CO₂ concentration. Its capacity in carbonate form is 0.86 mol of CO₂ per kilogram under 25 °C and 40 Pa. Langmuir model describes well the absorption isotherm at high saturation. The kinetics of CO₂ desorption dispersed in a flat sheet of polypropylene has been studied by experiments and models. We accounted for boundary layer transport limitations and made boundary layers thin enough to avoid such changes. The kinetic parameters of desorption, desorption coefficient and activation energy, are determined.