Developing adsorbents with multiple
merits in capacity,
selectivity,
mass transfer, and stability toward C2H2/CO2 separation is crucial and challenging for producing high-purity
C2H2 for advanced polymers and the electronic
industry. Here, we demonstrate a vertex strategy to create adsorbents
combining these merits through rationally designing the vertex groups
of a wavy-shaped framework in layered 2D metal–organic frameworks
(MOFs) to finely regulate the local conformation and stacking interactions,
which creates the optimal inter- and intralayer space to realize simultaneous
improvement of adsorption thermodynamics and kinetics. Two new hydrolytically
stable MOFs, ZUL-330 and ZUL-430, were prepared, and diverse experiments
and modeling on both adsorption equilibrium and diffusion were performed.
Record separation selectivities coupled with extraordinary dynamic
C2H2 capacities were achieved for C2H2/CO2 mixtures with different proportions
(50/50 or 10/5, v/v), along with a small diffusion barrier and fast
mass transfer. Consequently, polymer-grade (99.9%) and electronic-grade
(99.99%) C2H2 were obtained with excellent productivities
of up to ∼6 mmol cm–3.
The selective capture of C2H6 from
C2H6/C2H4 mixtures is
of critical
importance to realize the efficient one-step purification of C2H4 but remains challenging due to their similar
properties and smaller quadrupole moment of C2H6 that usually result in C2H4-preferring adsorption.
Herein, we reported two isostructural pillared-layer metal–organic
frameworks, ZUL-C3 and ZUL-C4, which were constructed by mixed polycycloalkane-type
ligands. Their low-polar pore environment along with more accessible
low-polar C–H binding sites on the pore surface are conducive
to generate more van der Waals interactions with C2H6 while the carboxylic groups distributed at four corners of
pores form stronger and more dipolar interactions with C2H6, cooperatively resulting in a good C2H6/C2H4 uptake ratio of 1.50 for ZUL-C3
and 1.72 for ZUL-C4 in static adsorption experiments and a high C2H4 (>99.99% purity) productivity of 10.1 L/kg
for
ZUL-C3 and 14.6 L/kg for ZUL-C4 from an equimolar C2H6/C2H4 mixture in breakthrough experiments.
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