Efficient and stable CO₂ capture using a scalable and spontaneous cross-linking amine-functionalized nano-Al₂O₃ adsorbent

Overcoming the challenges of efficiency and stability in amine-functionalized adsorbents for post-combustion CO2 capture is a pivotal goal. In this context, we propose a facile synthesis route for the polyethyleneimine (PEI)-functionalized nano-Al2O3 (PEI@Al2O3) adsorbent at a 1-ton scale, ensuring remarkable CO2 capture performance. By employing nano-Al2O3 as a support, we facilitate substantial PEI loading and induce spontaneous cross-linking of amine groups via Lewis acid sites, achieved through an innovative combination of aging and alcohol washing techniques. The cross-linking in PEI@Al2O3 effectively promotes the electron transfer from amine groups to the surface of nano-Al2O3, preventing the dehydration reaction of primary amines with CO2 to form isocyanate, thereby obtaining anti-urea properties for PEI@Al2O3. The resulting PEI@Al2O3 adsorbent exhibits excellent overall performance, including high CO2 uptake (195 mg g(-1)), fast adsorption kinetics (reaching near saturation within 10 min), consistently stable anti-urea cycling performance (with a mere 0.14% deactivation per cycle), environmentally friendly and scalable production (eliminating the need for expensive reagents), and competitive cumulative CO2 capacity (8.05 t t(-1) over 50 cycles). This breakthrough marks the advent of a new era for the advancement and practical utilization of cutting-edge amine-functionalized adsorbents.