Synthesis and Characterization of Porous Benzimidazole-Linked Polymers and Their Performance in Small Gas Storage and Selective Uptake

Porous organic polymers containing nitrogen-rich building units are among the most promising materials for selective CO 2 capture and separation which can have a tangible impact on the environment and clean energy applications. Herein we report on the synthesis and characterization of four new porous benzimidazole-linked polymers (BILPs) and evaluate their performance in small gas storage (H 2, CH 4, CO 2 ) and selective CO 2 binding over N 2 and CH 4 . BILPs were synthesized in good yields by the condensation reaction between aryl- o -diamine and aryl-aldehyde building blocks. The resulting BILPs exhibit moderate surface area (SA BET = 599–1306 m 2 g –1 ), high chemical and thermal stability, and remarkable gas uptake and selectivity. The highest selectivity based on initial slope calculations at 273 K was observed for BILP-2: CO 2 /N 2 (113) and CO 2 /CH 4 (17), while the highest storage capacity was recorded for BILP-4: CO 2 (24 wt % at 273 K and 1 bar) and H 2 (2.3 wt % at 77 K and 1 bar). These selectivities and gas uptakes are among the highest by porous organic polymers known to date which in addition to the remarkable chemical and physical stability of BILPs make this class of material very promising for future use in gas storage and separation applications.