A thiophene-containing covalent triazine-based framework with ultramicropore for CO2 capture

Abstract

In this work, a 2D covalent triazine-based framework was prepared by using 1,3-dicyanobenzo[c]thiophene (DCBT) as monomer to effectively capture CO2. The resulting CTF-DCBT was characterized by FT-IR, XPS, PXRD, elemental analysis, SEM, TEM, and N2 adsorption-desorption. The results indicate that CTF-DCBT is partially crystalline and has ultramicropore (6.5 Å) as well as high heteroatom contents (11.24 wt% and 12.61 wt% for N and S, respectively). In addition, the BET surface area and total pore volume of CTF-DCBT are 500 m2/g and 0.26 cm3/g, respectively. CTF-DCBT possesses excellent thermal stability (450 °C) and chemical stability towards boiling water, 4 M HCl, and 1 M NaOH. The CO2 adsorption capacity of CTF-DCBT is 37.8 cm3/g at 1 bar and 25 °C. After six adsorption–desorption cycles, there is no obvious loss of CO2 uptake observed. Due to the ultramicropore and high heteroatom contents, CTF-DCBT has high isosteric heats of adsorption for CO2 and high selectivities of CO2 over N2 and CH4. At 25 °C, the CO2/N2 and CO2/CH4 selectivities are 112.5 and 10.3, respectively, which are higher than those of most POFs. Breakthrough curves indicate that CTF-DCBT could effectively separate CO2/N2 and CO2/CH4 mixtures.