Newly designed 1,2,3-triazole functionalized covalent triazine frameworks with exceptionally high uptake capacity for both CO2 and H-2

Abstract

The search for efficient and high performing physisorbents for CO2 capture and separation from point sources as well as storage of cleaner gaseous fuels, such as H-2 and/or CH4, is considered to be a major challenge of numerous ongoing research activities in the domain of functional porous materials to avoid global warming via stabilizing the atmospheric CO2 level. Herein, a set of novel 1,2,3-triazole functionalized covalent triazine frameworks (TzCTFs) was synthesized under typical ionothermal conditions utilizing two rationally designed C3-symmetric triazole-substituted aromatic trinitrile building block analogues, namely Tz-FCN and Tz-HCN, with fluorinated and non-fluorinated phenyl core, respectively. A comparative and comprehensive elucidation to the effect of building block functionalities on the textural and gas uptake properties of resulting TzCTFs has been discussed. TzCTF materials synthesized at 600 degrees C give rise to significantly higher BET surface area (df-TzCTF600: 1720 m(2) g(-1) and TzCTF600: 1582 m(2) g(-1)) compared to the TzCTF400 (874 m(2) g(-1)) and df-TzCTF400 (906 m(2) g(-1)) material synthesized at 400 degrees C. The dominating ultra-micropores in the range of 0.45-0.9 angstrom, together with embedded various CO2-phillic basic trizolic, triazine, and pyrrolic N-species, were synergistically endowed with an exceptionally high uptake of both CO2 (up to 6.79 m mol g(-1) at 273 K) and H-2 (up to 2.50 wt% at 77 K) under the pressure of 1 bar. Notably, the df-TzCTF600 with CO2 uptakes of 4.60 mmol g(-1) (298 K, 1 bar) and 6.79 mmol g(-1) (273 K, 1 bar), along with H-2 uptake capability of 2.50 wt% (77 K, 1 bar), ranks highest among all related CTF-based adsorbents under identical conditions to date. The methane uptake capacity of df-TzCTF600 (4.37 wt% at 273 K, 1 bar) is also impressive and represents the second highest among all porous organic polymers. Moreover, TzCTFs exhibit moderately high CO2 selectivity over N-2 with a CO2/N-2 selectivity of up to 27 (Henry) and 40 (IAST) at 298 K. Finally, the obtained novel TzCTF materials in combination with facile modular synthesis via rationally designed building blocks, high thermal and chemical stability, and excellent CO2, H-2 and CH4 uptake and separation capabilities make them promising task-specific adsorbents for various potential applications.