Host–Guest Pore Space Partition in a Boron Imidazolate Framework for Ethylene Separation

Separation
of ethylene (C2H4) from ethane
(C2H6) through one step is desirable but challenging
in view of their similar sizes and physical properties. Introduction
of pore partition agents into metal–organic frameworks (MOFs)
endows materials with multivariate porous environments for gas adsorption
and separation. Here, we report a novel microporous boron imidazolate
framework (BIF-108-Zn) that integrates both organic ligands and extra-framework
species as pore partition agents to divide the interconnected channels
into isolated cages. This structure possesses a high pore volume with
a reduced pore size and a functionalized pore surface to realize preferential
binding of C2H6 over C2H4. Dynamic breakthrough measurements demonstrated that BIF-108-Zn
can directly produce polymer-grade C2H4 with
a productivity of 0.69 mmol/g at 298 K and 1 bar from a binary mixture
of C2H6/C2H4. Furthermore,
the relatively low isosteric enthalpy value endows it with good regenerability
and high stability, as verified by multiple adsorption separation
tests.