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

Abstract

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.