A facile synthesis of microporous organic polymers for efficient gas storage and separation

Abstract

A series of porous hyper-cross-linked polymers with excellent physiochemical stability have been designed and prepared facilely through template-free Friedel–Crafts alkylation reactions between benzene/biphenyl/1,3,5-triphenylbenzene as co-condensing rigid aromatic building blocks and 1,3,5-tris(bromomethyl)benzene or 1,3,5-tris(bromomethyl)-2,4,6-trimethylbenzene as cross-linkers under the catalysis of anhydrous AlCl₃ or FeCl₃. The systematic study of gas uptake ability shows that anhydrous AlCl₃ is a much more effective catalyst than anhydrous FeCl₃. The synthesized polymers are thermally stable and are predominantly microporous with high surface areas up to 1783 m² g⁻¹. In addition, they exhibit high H₂ and CO₂ uptake capacity/selectivity. Among these materials, C1M3-Al has the highest H₂ uptake capacity at 77 K and 1 bar (19.1 mg g⁻¹) and CO₂ uptake capacity at 273 K and 1 bar (181 mg g⁻¹); the best CO₂/N₂ (15/85) selectivity calculated by IAST at 273 K and 1 bar belongs to C1M2-Al (32.3). Moreover, the synthesis route exhibits cost-effective advantages, which are essential for scale-up preparation, thus showing great potential for clean energy applications.