Reticular Chemistry in Pore Engineering of a Y‑Based Metal–Organic Framework for Xenon/Krypton Separation

The fine-tuning of metal–organic framework (MOF)
pore structures
is of critical importance in developing energy-efficient xenon/krypton
(Xe/Kr) separation techniques. Capitalizing on reticular chemistry,
we constructed a robust Y-based MOF (NU-1801) that is isoreticular
to NPF-500 with a shortened organic ligand and a larger metal radius
while maintaining the 4,8-connected flu topology, giving
rise to a narrowed pore structure for the efficient separation of
a Xe/Kr mixture. At 298 K and 1 bar, NU-1801 possessed a moderate
Xe uptake of 2.79 mmol/g but exhibited a high Xe/Kr selectivity of
8.2 and an exceptional Xe/Kr uptake ratio of about 400%. NU-1801 could
efficiently separate a Xe/Kr mixture (20:80, v/v), as validated by
breakthrough experiments, due to the outstanding discrimination in
van der Waals interactions of Xe and Kr toward the framework confirmed
by grand canonical Monte Carlo simulations. This work highlights the
importance of reticular chemistry in designing structure-specific
MOFs for gas separation.