Topology-Dependent Alkane Diffusion in Zirconium Metal–Organic\nFrameworks

Abstract

Metal–organic frameworks (MOFs) can be designed for chemical\napplications by modulating the size and shape of intracrystalline\npores through selection of their nodes and linkers. Zirconium nodes\nwith variable connectivity to organic linkers allow for a broad range\nof topological nets that have diverse pore structures even for a consistent\nset of linkers. Identifying an optimal pore structure for a given\napplication, however, is complicated by the large material space of\npossible MOFs. In this work, molecular dynamics simulations were used\nto determine how a MOF’s topology affects the diffusion of\npropane and isobutane over the full range of loadings and to understand\nhow MOFs can be tuned to reduce transport limitations for applications\nin separations and catalysis. High-throughput simulation techniques\nwere employed to efficiently calculate loading-dependent diffusivities\nin 38 MOFs. The results show that topologies with higher node connectivity\nhave reduced alkane diffusivities compared to topologies with lower\nnode connectivity. Molecular siting techniques were used to elucidate\nhow the pore structures in different topologies affect adsorbate diffusivities.