Precise Pore Space Partitions Combined with High-Density Hydrogen-Bonding Acceptors within Metal-Organic Frameworks for Highly Efficient Acetylene Storage and Separation

摘要

The high storage capacity versus high selectivity trade-off barrier presents a daunting challenge to practical application as an acetylene (C2H2) adsorbent. A structure-performance relationship screening for sixty-two high-performance metal-organic framework adsorbents reveals that a moderate pore size distribution around 5.0-7.5 angstrom is critical to fulfill this task. A precise pore space partition approach was involved to partition 1D hexagonal channels of typical MIL-88 architecture into finite segments with pore sizes varying from 4.5 angstrom (SNNU-26) to 6.4 angstrom (SNNU-27), 7.1 angstrom (SNNU-28), and 8.1 angstrom (SNNU-29). Coupled with bare tetrazole N sites (6 or 12 bare N sites within one cage) as high-density H-bonding acceptors for C2H2, the target MOFs offer a good combination of high C2H2/CO2 adsorption selectivity and high C2H2 uptake capacity in addition to good stability. The optimized SNNU-27-Fe material demonstrates a C2H2 uptake of 182.4 cm(3) g(-1) and an extraordinary C2H2/CO2 dynamic breakthrough time up to 91 min g(-1) under ambient conditions.