Molecular Simulation Studies Of Gas Eparation In Metal-Organic Frameworks With Nterpenetration And Multi-Linker

Metal-Organic Frameworks （MOFs） have shown promising applicationsin gas storage, separation, catalyst, biochemistry and pharmacy and so on, dueto their extensive class, highly ordered structure, adjustable pore sizes,devisable surface functional groups and surface potential. Over ten thousandkinds of MOFs have been synthesized, and most have complex structure, andthus only with experimental method is difficult to perform systematic andcomprehensive study. In recent years, molecular simulation techniques havebeen widely used in the study of the relations between structure and propertyin MOFs, and provided useful information for materials design and synthesis,and also can be used for pre-screening of materials, greatly facilitate thepractical application of MOFs.In this work, molecular simulation was used to study industrial gasmixtures separation in MOFs. The main contents and findings are summarizedas follows:（1） The adsorption separation of nC₄/iC₄and nC₅/iC₅in three pairs ofMOFs with and without interpenetration （Zn（L5）₂（L1） and Zn（L6）₂（L1）, IRMOF-13and IRMOF-14, PCN-6and PCN-6′） is studied using molecularsimulation at room temperature. The calculation results of the adsorptionselectivity show that interpenetration may not be beneficial for separation ofalkane isomers （nC₄/iC₄and nC₅/iC₅）, which is not the same as in the case forthe light gas mixtures. We found that the effect of interpenetration on theselectivity of alkane isomers largely depends on the preferential adsorptionpore size. With the decrease of pore size, the selectivity increases at first, andthen reaches the maximum value, followed by the further decreases.（2） Molecular simulation was performed to study CH₄/H₂mixtureseparation and CO₂capture from various practical systems in four pairs ofmulti-linker MOFs with and without interpenetration at room temperature.That the results show that adsorption selectivity is much enhanced in themulti-linker MOFs with interpenetration compared with their multi-linkerMOFs without interpenetration, which is consistent with the case insingle-linker MOFs. But adsorption selectivity in multi-linker MOFs withinterpenetration increases much more than that in single-linker MOFs withinterpenetration. Furthermore, we found that adsorption selectivity is notaffected by exist of multi-linker, and molecular-level segregation is only foundin multi-linker MOFs.