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Percorrer por autor "Freitas, Francisco A. Da Silva"

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  • Experimental and dynamic modeling study of CO2/N2 separation on ion-exchanged binder-free LTA zeolites for post-combustion carbon capture
    Publication . Karimi, Mohsen; Aly, Ezzeldin; Rodrigues, Alírio E.; Freitas, Francisco A. Da Silva; Silva, José A.C.
    Ion-exchange modification of commercial binder-free zeolites offers a promising strategy to improve adsorption-based CO2 capture from post-combustion flue gases. In this study, the CO2/ N-2 separation performance of ion-exchanged binder-free Linde-Type A (LTA) zeolites-namely 4 A, 5 A, Sr(40)A, and Sr(80)A-was systematically evaluated under post-combustion capture (PCC) conditions. Adsorption isotherms were measured over the temperature range of 306-344 K and pressures up to 350 kPa. The CO2 uptake followed the order: 5 A > Sr(40)A > Sr(80)A > 4 A, with 5 A achieving the highest loading of 5.58 mol center dot kg(-1) at 120 kPa and 306 K, compared to 4.47 mol center dot kg(-1) for Sr(40)A, 4.45 mol center dot kg(-1) for Sr(80)A, and 3.73 mol center dot kg(-1) for 4 A. The presence of divalent cations (Ca2+ and Sr2+) strengthened the electrostatic interactions, thereby enhancing CO2 affinity relative to the Na-exchanged 4 A. Binary CO2/N-2 breakthrough experiments demonstrated that Sr(80)A exhibited the highest selectivity (75 at 10 kPa and 306 K), followed by 5 A (60), 4 A (51), and Sr(40)A (47). Which the developed mathematical model accurately captured the breakthrough behavior and dynamic performance of the fixed-bed system. Finally, a Response Surface Methodology (RSM) was applied to the statistical analysis of selectivity of different studied zeolites and getting the optimum operating conditions.
    2026Artigo científico Acesso aberto Ver mais