Molecular simulations of COFs, IRMOFs and ZIFs for adsorption-based separation of carbon tetrachloride from air.

Covalent organic frameworks (COFs), metal organic frameworks (MOFs) and zeolitic imidazolate frameworks (ZIFs) have been widely studied in gas separation applications due to their large surface areas, high pore volumes, tunable pore sizes and chemical stabilities. In this study, separation performances of 153 COFs, 14 IRMOFs and 8 ZIFs were assessed for efficient removal of carbon tetrachloride (CCl) from CCl/Ar, CCl/N, CCl/O mixtures at 298 K and infinite dilution. The top performing three materials in each group, namely, borazine-linked polymer (BLP-2H-AA), IRMOF-11 and ZIF-6 were identified. Single-component, binary mixture and quaternary mixture adsorption isotherms of argon (Ar), CCl, nitrogen (N) and oxygen (O) in these materials were computed at 298 K and various total pressures from 10 to 1.5 × 10 kPa. Mixture adsorption selectivities and separation potentials were then calculated and the effect of relative humidity on the performance of adsorption-based CCl separation was examined. Single-component and quaternary mixture diffusion coefficients of Ar, CCl, N and O were finally computed. Our results showed that ZIF-6 exhibits the highest adsorption selectivity and the highest separation potential for CCl/Ar, CCl/N and CCl/O mixtures, followed by IRMOF-11 and BLP-2H-AA. Results of this computational study will be highly useful to identify the promising materials for removal of CCl from air.