Mild preparation of structured solid amine adsorbent pellets with the assistance of alginate for efficient and stable CO₂ adsorption

The industrialization of solid amine adsorbents requires the molding of the adsorbents, and the blockage or collapse of the pore structure caused by the molding process will inevitably affect the CO₂ adsorption performance. Herein, the structured solid amine adsorbent pellets (SA-T/M) were fabricated based on the crosslinking of alginate and Ca²⁺ under mild conditions. The pelletized SA-T/M well preserved the pore structure of the original support, with only a 26.8 % diminution in specific surface area, which profited to a more uniform loading and dispersion of amine. Benefitting from the influence of pore structure on amine dispersion, SA-T/M achieved a pretty CO₂ adsorption capacity of 2.49 mmol g⁻¹. The hydroxyl group of alginates can form hydrogen bonds with the amines, which greatly improved the amine stability of the adsorbent and enabled SA-T/M to exhibit excellent cyclic stability. After 30 adsorption-desorption cycles, the adsorption capacity of SA-T/M merely decreased by 15.6 %. Considering the adsorption capacity and stability of structured adsorbents, the molding strategy with the assistance of alginate provides a potential path for the industrial application of solid amine adsorbent molding technique.