Triazine-based microporous polymers for selective adsorption of CO2

Abstract

Propeller-shaped triazine was used to synthesize microporous polycarbazole materials through an inexpensive FeCl3-catalyzed reaction using direct oxidative coupling (PCBZ) and extensive cross-linking (PCBZL) polymerization routes. PCBZL has a Brunauer-Emmett-Teller specific surface area of 424 m2 g-1 and shows larger CO2 uptake (64.1 mg g-1 at 273 K, 1 atm). Selective adsorption of CO2 over N2 calculated using the ideal adsorbed solution theory shows that both PCBZ (125) and PCBZL (148) exhibit selectivity at 298 K, which is significantly higher than PCBZ (110) and PCBZL (82) at 273 K. These values of selectivity are among the highest reported for any triazine-based microporous material. By introducing the electron-rich carbazole structure into the nitrogen fertile triazine-based system, the adsorption enthalpy is increased drastically, which in turn contributes to high selective adsorption values. The larger existing binding energy between CO2 and propeller specifies more stable and favorable interactions between adsorbent and adsorbate, which transforms into reasonable adsorption capacity at low pressure and eventually high selectivity. These polymeric networks also show moderate working capacity with high regenerability factors. The combination of a simple inexpensive synthesis approach, high thermal/chemical stability, and reasonable selective adsorption make these materials potential candidates for CO2 storage and separation applications.