Benzimidazole functionalized covalent triazine frameworks for CO2 capture

A series of covalent triazine frameworks containing benzimidazole segments (CTF-BIs) were designed and prepared by dynamic trimerization under ionothermal conditions, based on the novel designed dicyano monomer of dicyano benzimidazole (DCBI). The CTF-BIs were all amorphous and exhibited BET surface areas up to 1549 m2 g-1. The effect of reaction conditions including the ratio of catalyst and temperature on the pore properties was discussed. Meanwhile, the CO2 adsorption capacity of all the CTF-BIs was studied and it was found that the CO2 uptake capacity was as high as 21.68 wt% at 273 K and 1.10 bar for CTF-BI-11. The CTF-BIs exhibited high selectivities for CO2 over N2 in the range of 31.3-88.5 at 273 K, and 29.0-102.7 at 303 K, respectively.