posted on 2020-12-03, 15:06authored byBrandon
C. Bukowski, Randall Q. Snurr
Metal–organic frameworks (MOFs) can be designed for chemical
applications by modulating the size and shape of intracrystalline
pores through selection of their nodes and linkers. Zirconium nodes
with variable connectivity to organic linkers allow for a broad range
of topological nets that have diverse pore structures even for a consistent
set of linkers. Identifying an optimal pore structure for a given
application, however, is complicated by the large material space of
possible MOFs. In this work, molecular dynamics simulations were used
to determine how a MOF’s topology affects the diffusion of
propane and isobutane over the full range of loadings and to understand
how MOFs can be tuned to reduce transport limitations for applications
in separations and catalysis. High-throughput simulation techniques
were employed to efficiently calculate loading-dependent diffusivities
in 38 MOFs. The results show that topologies with higher node connectivity
have reduced alkane diffusivities compared to topologies with lower
node connectivity. Molecular siting techniques were used to elucidate
how the pore structures in different topologies affect adsorbate diffusivities.