Characterization and Performance of Direct Air Capture Sorbent

In this paper, a proprietary CO2 sorbent is characterized and its sorption capacity determined. FTIR-ATR spectroscopy suggests that the sorbent is composed of polystyrene functionalized with primary amine. The Toth isotherm is found to best fit to laboratory-scale CO2 sorption data in partial pressure range of 0.1-5 mbar. Chemisorption dominates at and below atmospheric CO2 partial pressure, especially in humid conditions. Humidity promotes total CO2 capacity by 20-34%. Temperature-dependent Toth model is used to estimate working capacity in different regeneration conditions. Temperature swing adsorption or temperature-vacuum swing adsorption can be utilized in direct air capture conditions, depending on the application