Rational design and synthesis of covalent triazine frameworks based on novel N-heteroaromatic building blocks for efficient CO2 and H2 capture and storage

Covalent Triazine Frameworks (CTFs), a nitrogen-rich subclass of Porous Organic Polymers (POPs), show large potential in applications including gas adsorption /separation and heterogeneous catalysis due to their distinctive large surface area, low skeleton density, good thermal and chemical stability combined with their rational tunability.1 Herein, we reported on a set of nitrogen-rich CTFs prepared by trimerization of 4,4',4'',4'''-(1,4-phenylenebis(pyridine-4,2,6-triyl))tetrabenzonitrile under ionothermal conditions. The influence of several parameters such as ZnCl2/monomer ratio and reaction temperature on the structure and porosity of the resulting frameworks was systematically examined. After a thorough characterization, their performance in CO2 and H2 adsorption as well as their selectivity of CO2 over N2 was assessed. Notably, the CTF obtained using 20 molar equiv. of ZnCl2 at a reaction temperature of 400 ºC exhibits an excellent CO2 adsorption capacity (3.48 mmol/g at 273 K and 1 bar) as well as a significant high H2 uptake (1.5 wt% at 77 K and 1 bar). These values are among the highest measured under identical conditions to date. In addition, the obtained CTFs also present a relatively high CO2/N2 selectivity (up to 36 at 298 K) making them promising adsorbents for gas sorption and separation.