Integrated material and process evaluation of metal–organic frameworks database for energy-efficient SF₆/N₂ separation

In this work, we proposed multi-scale screening, which employs both molecular and process-level methods, to identify high-performing MOFs for energy-efficient separation of SF₆ and N₂ mixture. Grand canonical Monte Carlo (GCMC) simulations were combined with ideal adsorption process simulation to computationally screen 2890 metal–organic frameworks (MOFs) for adsorptive separation of SF₆/N₂. More than 150 high-performing MOFs were identified based on the GCMC simulations at the pressure and vacuum swing conditions, and subsequently evaluated using the ideal adsorption process simulation. 78 out of 86 MOFs selected for the VSA conditions were able to achieve the 90% target purity level of SF₆, but 62 top-performing MOFs selected for the PSA condition could not reach the purity level with a single train PSA configuration. Cascade PSA configuration was proposed and adopted to improve the purity level. We also investigated the effect of vacuum pump and compressor efficiency on the energy consumption of the process. We found that the top-performing MOFs were able to achieve the 90% purity-level of SF₆ with 0.10–0.4 and 0.5–1.4 MJ per kg of SF₆ for VSA and PSA processes, respectively. Finally, the process-level performance of top-performing MFOs (HKST-1, UiO-67) was evaluated on the basis of the experimental isotherms obtained from the literature, and compared with the other materials reported in the literature (MIL-100(Fe), UiO-66, and zeolite-13X). We found that the results based on the experimental isotherms are in qualitative agreement with the results based on the simulated isotherms.