Nitrogen-bridged covalent triazine polymer for highly selective CO2 capture

Nitrogen-bridged covalent triazine polymers NB-CTP-1 and NB-CTP-2 were designed and synthesized from tris(4-cyanamidophenyl)amine and tetrakis(4-cyanamidophenyl)methane to address the issue of trade-off between CO2 adsorption capacity and CO2/N2 adsorption selectivity among the well-established organic polymers. The structure and morphology features of the prepared samples were characterized by means of FTIR, TGA, XRD, SEM, TEM and automatic physical adsorption analyzer. The NB-CTP materials showed good CO2 adsorption capacities (3.04 mmol/g for NB-CTP-1, 3.23 mmol/g for NB-CTP-2) under 1.01×105 Pa and 273 K conditions. Based on the reversible adsorption-desorption isotherms at 1.01×105 Pa and 273 K, CO2/N2 selectivity for NB-CTP-1 was obtained as high as 113 (Henry's law) and 143 (IAST), whereas for NB-CTP-2, it was 75 (Henry's law) and 89 (IAST). In addition, the enthalpy of adsorption at zero coverage for NB-CTP-1 (35.3 kJ/mol) and NB-CTP-2 (37.6 kJ/mol) were calculated using the Vant Hoff equation based on Virial equation, revealing the strong dipole-quadrupole interactions between these materials and CO2, which could enhance the CO2/N2 adsorption selectivity. © 2021, Editorial Office of FINE CHEMICALS. All right reserved.