Amine-modified SBA-15: Effect of pore structure on the performance for CO₂ capture

Several SBA-15 silica materials with different pore structures were synthesized and functionalized with poly(ethyleneimine) (PEI). The as-prepared materials were characterized by XRD, SEM, TG, FT-IR, and N₂ physisorption techniques followed by testing for CO₂ capture using a N₂ stream containing 15.1 v/v% CO₂ in the temperature range of 30-75 °C. The results showed that the CO₂ adsorption capacity linearly increased with the total pore volume of the SBA-15 phases in the tested temperature range (R² > 0.94). Temperature also showed a strong influence on CO₂ adsorption capacity. SBA-15 material with the largest pore volume (1.14 cm³ g^-1) exhibited the largest CO₂ adsorption capacity (105.2 mg g^-1 adsorbent) with 15.1 v/v% CO₂ in N₂ at 75 °C and atmospheric pressure. Pore size was found not to be the main factor influencing the CO ₂ adsorption capacity of these PEI-modified SBA-15 materials. Adsorption-desorption cycles (12) revealed that the adsorbents with PEI loaded inside the pore channels were found to be quite stable, as they retained their CO₂ adsorption capacity with many cycles.