(376be) CO2 Adsorption Performance of Functionalized Metal-Organic Frameworks with Different Topologies By Molecular Simulations

Anthropogenic carbon dioxide (CO₂) is the major greenhouse in the atmosphere that leads to global climate change. Metal-organic frameworks (MOFs) are regarded as a promising means to efficiently capture CO₂. The Multivariate MOFs (MTV-MOFs) consisting of a variety of organic linker functionalized by multiple functional groups could exhibit better performance in carbon capture and separation (CCS). In order to understand the effect of the framework topology and mixed functionalities on the CCS performance, Zr-MOFs in three topologies (csq, ftw, scu) with each composed by one of the three types of linkers of different lengths were constructed, and then functionalized by three types of functional groups (–F, –NH₂, –OCH₃), respectively. Grand canonical Monte Carlo (GCMC) simulations were used to investigate CO₂ adsorption performance of all created MOFs. We revealed that among the parent MOFs consisted of identical building blocks but in different topologies, ftw-MOFs exhibit the highest CO₂ working capacity and CO₂/N₂ selectivity due to the strong affinity towards CO₂. Moreover, the CO₂ adsorption performance of ftw-MOFs shows obvious dependence on the pore size, consistent with their host-adsorbate interaction energy, which is not the fact for csq-MOFs and scu-MOFs. The enhanced CO₂ adsorption performance upon functionalization of MOFs displays pore-size dependence as well, especially for –NH₂ functionalized frameworks in csq and scu, which is mostly attributed to the enhanced host-adsorbate Coulombic interaction. The proposed effects of the topology, the pore size and the functional group of MOFs on CO₂ adsorption performance obtained in this study may provide meaningful insight into the rational design of high-performing MOFs for carbon capture by tuning the topology, pore size and functionality of frameworks.