Designing large-sized and spherical CO2 adsorbents for highly reversible CO2 capture and low pressure drop

[Display omitted] •The well-interconnected porous adsorbent was synthesized in a millimeter-sized sphere.•The synthesized spherical adsorbent has amine and hydroxyl groups together.•Harmonious amine/hydroxyl groups allowed highly reversible CO2 adsorption/desorption.•Low pressure drop was achieved by a well-designed interior structure of the adsorbent.•The adsorbent showed high CO2 selectivity for the CO2/N2 mixture. To enhance the processing efficiency of CO2 capture from flue gas of post-combustion emission using fixed-bed adsorption system, the regenerable adsorbents and low pressure drop should be required. The uniform-sized Polyacrylonitrile (PAN) nanoparticles were synthesized, followed by the surface-modification with alkylamine (APAN) and sec-butanol (APAN-OH) as a strategy for achieving the stabilization of the amine group in the repeated CO2 adsorption/desorption cycles. The synthesized APAN-OH nanoparticles were interconnected one another by Ca-Alg nanofiber as a linker and formed the millimeter-sized sphere with hierarchical pores. At 25 °C and 1 bar, CO2 adsorption capacity of a Hierarchically porous spherical adsorbent (HPSA) reached to ~2.07 mmol CO2/g HPSA and physicochemical stability of HPSA was achieved even in 50 cycles of CO2 adsorption/desorption. Also, the selectivity for CO2 capture was calculated as about 71 by the IAST model at CO2/N2 molar ratio of 15:85. Extremely low pressure drop values were recorded in the fixed-bed adsorption system packed with HPSAs, compared with those of APAN-OH nanoparticles. The superior regenerable and large-sized adsorbent with the interior structure resulting in low pressure drop is expected to take the CO2 capture technology a step further.