Novel triazine carbonyl polymer with large surface area and its polyethylimine functionalization for CO₂ capture

Incorporating high density of nitrogen and amine sites into a proper porous structure is a major consideration for developing CO₂ adsorbents. Herein, a novel triazine carbonyl polymer (TCP) was synthesized via one pot Friedel-Crafts reaction and then was post-synthetically functionalized with polyethylimine (PEI) to develop TCP-PEI. The successful syntheses of TCP and TCP-PEI were verified by various characterizations, including FT-IR, XPS, SEM/EDS, and N₂ adsorption isotherms at 77 K. The pristine TCP displayed hierarchical pores and a significantly large BET surface area (1940 m²/g), which verified its propriety of being utilized as a support for PEI functionalization. As reasoned, TCP-PEI showed significantly stronger CO₂ adsorption than the pristine TCP because of the special interaction between CO₂ and PEI. As a result, TCP-PEI exhibited considerably higher CO₂/N₂ and CO₂/CH₄ selectivities than TCP. Moreover, it showed almost identical CO₂ adsorption isotherms for 5 consecutive cycles. Developing covalent porous polymers with both triazine and carbonyl groups and follow-up PEI functionalization would be an efficient strategy for developing CO₂ adsorbents.