Judicious design functionalized 3D-COF to enhance CO2 adsorption and separation.

The effects of functional groups (including OH, OCH3 , NH2 , CH2 NH2 , COOH, SO3 H, OCO(CH2 )2 COOH(E-COOH), and (CH2 )4 COOH(c-COOH)) in 3D covalent organic frameworks (3D-COFs) on CO2 adsorption and separation are investigated by grand canonical Monte Carlo (GCMC) simulations and density functional theory calculations. The results indicate that interaction between CO2 and the framework is the main factor for determining CO2 uptakes at low pressure, while pore size becomes the decisive factor at high pressure. The binding energy of CO2 with functionalized linker is correlated to CO2 uptake at 0.3 bar and 298 K on 3D-COF-1, suggesting functional groups play a key role in CO2 capture in microporous 3D-COFs. Moreover, CO2 selectivity over CH4 , N2 , and H2 can be significantly enhanced by functionalization, where CH2 NH2 , COOH, SO3 H, and E-COOH enhance CO2 adsorption more effectively at 1 bar. Among them, SO3 H is the most promising functional group in 3D-COFs for CO2 separation.