Design of thermo-responsive hyperbranched nanofibre-based adsorbent with high CO2 adsorption capacity and analysis of its ultra-low temperature regeneration mechanism

Thermo-responsive solid amine adsorbents are used for adsorption of CO2 in carbon capture and storage. They have a low temperature regeneration, but are incapable of high CO2 adsorption capacity because of the imbalance between the densities of the amino and thermo-responsive groups. Hence, a novel thermo-responsive hyperbranched intelligent nanofibre-based adsorbent was designed via cross-linking with a hyperbranched polyamine and a thermo-responsive intelligent nanofibre. The liquid–solid phase one-step rapid conversion used here balanced the high amino density (12.40 mmol g−1) with that of the synergistic groups (thermo-sensitive groups, 3.12 mmol g−1, and hydroxyl groups, 4.35 mmol g−1) of the adsorbent. A high-efficiency diffusion kinetics was maintained, and the conversion rate of the reactants reached 99%. An in situ variable-temperature characterisation and density functional theory (DFT) analysis were performed. The adsorbent possessed high CO2 adsorption capacity (6.23 mmol g−1) and ultra-low regeneration temperature (60 °C), the lowest regeneration temperature reported in the literature to date. These were attributed to the specialized and cooperative mechanism between amino, hydroxyl, and thermo-responsive groups of the adsorbent.