High-throughput computational screening of covalent organic frameworks for gas separations

Capture of CO2 from flue gas and the purification of natural gas are environmentally and economically crucial. Covalent organic frameworks (COFs) are a newly emerging family of nanoporous materials in which light elements (B, C, N, O, H) are connected by strong covalent bonds. Due to their various structural properties, COFs gained a lot of attention for gas separation applications over the last decade. However, the large number of experimentally synthesized COFs makes it nearly impossible to measure the gas separation potentials of each COF material. Thus, we used a high-throughput computational approach in this thesis to assess the CO2/N2, CH4/H2, CH4/N2 and C2H6/CH4 separation performances of COFs. First, grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations were performed to investigate the adsorption- and membrane-based CO2/N2 separation performance of 295 COFs. Results elucidated that COFs could outperform traditional adsorbents such as zeolites and activated carbons for CO2/N2 separation. According to the structure-performance relations, COFs with pore sizes<10 Å, 0.6CH4>N2>H2, in accordance with molecular simulation results, and the degree of linker aromaticity could be used to identify the highly alkane selective COFs. These results show that COFs could outperform traditional adsorbent and membrane materials for gas separation processes. The findings of this thesis will pave the way for future computational and experimental studies to identify the most promising COF candidates and to design new materials with high gas separation potentials.