Grafting Poly(ethyleneimine) on Macroporous Core–Sheath Copolymer Beads with a Robust Framework for Stable CO2 Capture under Low-Temperature Regeneration

A macroporous organic adsorbent was designed and prepared using the template method, with acrylamide (AM) as the skeleton, glycidyl methacrylate (GMA) as the shell, and F-127 and Pluronic block copolymer (P123) as surfactants, and grafted with polyethyleneimine (PEI). Solid adsorbents were used for carbon dioxide capture. The effect of the AM/GMA mass ratio on the spherical morphology, through-hole structure, specific surface area, hardness, hydrophobicity, and thermal stability was comprehensively investigated, and the CO2 adsorption performance of the PEI-modified adsorbent was studied. Surface area and morphology characterization showed that after the introduction of GMA, the wall thickness and roughness increased, and the specific surface area and the mass of GMA first showed a positive correlation and then a negative correlation. In addition, the thermal stability was slightly reduced, and the hydrophobicity was greatly improved. The CO2 adsorption results revealed that the organic adsorbents exhibited higher adsorption capacity and faster adsorption kinetics than conventional CO2 capture materials, and their simple synthesis enables their industrial application. The study revealed that the preparation of PEI-modified adsorbents with a core–shell structure greatly improved thermal stability and selectivity. When the PEI loading was 50 wt %, the CO2 capacity of the core–shell microspheres reached 3.11 mmol·g–1 at 40 °C, and desorption can be completed at 85 °C. The proposed material has a good industrial application prospect and shows an excellent lifetime performance.