Phenylamino-, Phenoxy-, and Benzenesulfenyl-Linked Covalent Triazine Frameworks for CO<sub>2</sub> Capture
Chonglingyun Liao, Zhongshuai Liang, Bei Liu, Hongbiao Chen, Xueye Wang, Huaming Li
Abstract
Covalent triazine-based frameworks (CTFs) have emerged as an important class of adsorbents for CO2 capture and storage and have garnered a great deal of attention. However, the systematic study of the relationship between PhNH-, PhO-, and PhS-linked CTFs and CO2 uptake performance has not yet been conducted. We herein report the synthesis and CO2 uptake performance of such CTFs. Three similarly structured, nitrile-containing monomers including 2,4,6-tris(4-cyanophenylamino)-1,3,5-triazine (TAT), 2,4,6-tris(4-cyanophenoxy)-1,3,5-triazine (TOT), and 2,4,6-tris(4-cyanobenzenesulfenyl)-1,3,5-triazine (TST) have been employed to synthesize such CTFs through ZnCl2-mediated cyclotrimerization by a stepwise heating method for the purpose of keeping the CTF structure intact. The CO2 capture performances of such CTFs are confirmed to rely on the incorporated heteroatoms and increase in the order of PhNH- > PhO- > PhS-linkage in CTFs. A theoretical calculation demonstrates the same trend of the CO2 binding energies and are found to be −20.7, −19.3, and −13.5 kJ mol–1 respectively for PhNH-, PhO-, and PhS-bridged CTFs. In addition, the PhNH-linked CTF prepared at high temperature (600 °C) displays a much higher CO2 adsorption capacity (5.0 mmol g–1 at 273 K/1 bar).