ETHYLENE/ETHANE SEPARATION IN METAL-ORGANIC FRAMEWORK BY COMPUTATIONAL MODELING
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Metal-organic frameworks (MOFs) with open metal sites (OMS) are known to have selectivity in olefin/paraffin separations because of π-π interactions between olefin double bonds and OMS. This dissertation utilized computational methods to accomplish three goals: (1) screening MOF materials with open metal sites for ethylene/ethane separation; (2) test the adsorption performance of promising MOF materials with OMS for the multicomponent separation; and (3) estimate their process performance. We first used Density Functional Theory (DFT) to assess the binding energy of ethylene, water, and carbon monoxide on a set of more than 60 MOFs with open Cu sites in the form of Cu dimers. The main observation is that MOF topology and linker species are secondary factors in determining the binding energy. We further used metal substitution and linker functionalization to tune the relative binding affinities in MOFs with OMS, which is turned to be more effective. Mixed-metal strategy is proved to be promising to tune the binding affinity of guest molecule in bimetallic systems. The process performance of the materials was also estimated with idealized and full pressure swing adsorption models. Additionally, materials based on kinetic ethylene/ethane separation were also investigated in this dissertation. This work paves the way for more robust material design for ethylene/ethane separation.