An ethylenediamine-grafted Y zeolite: a highly regenerable carbon dioxide adsorbent via temperature swing adsorption without urea formation

Abstract

Solid adsorbents including amine-functionalized porous materials and zeolites have been extensively investigated for post-combustion CO₂ capture. Amine-functionalized porous materials have shown highly promising CO₂ uptake in a wet flue gas, but suffer from significant amine deactivation due to urea formation under desorption conditions (e.g., desorption under 100% CO₂ at >130 °C) of temperature swing adsorption (TSA) cycles. In contrast, purely inorganic zeolites are thermochemically stable but cannot adsorb CO₂ from a wet flue gas because of the preferential H₂O adsorption. In the present work, we synthesized an ethylenediamine-grafted Y zeolite, which can synergistically combine the strengths of both adsorbent systems. The amine groups can effectively capture CO₂ in a wet flue gas, while the strongly co-adsorbed H₂O within the hydrophilic zeolite micropores suppresses urea formation (dehydration reaction between amines and CO₂) under desorption conditions according to Le Chatelier's principle. The organic–zeolite hybrid adsorbent retains working capacities higher than 1.1 mmol g⁻¹ over 20 TSA cycles. Because the adsorbent is prepared from a commercially available zeolite, it is also highly cost efficient and suitable for mass production.