Switchable Xe/Kr Selectivity in a Hofmann-Type Metal-Organic Framework via Temperature-Responsive Rotational Dynamics

Authors
Kim, HyojinChoe, Jong HyeakKang, MinjungKang, Dong WonYun, HongryeolYoun, JeongwonLee, Weon-GyuLee, Jung-HoonHong, Chang Seop
Issue Date
2023-08
Publisher
Wiley - V C H Verlag GmbbH & Co.
Citation
Small, v.19, no.35
Abstract
The development of adsorbents for Kr and Xe separation is essential to meet industrial demands and for energy conservation. Although a number of previous studies have focused on Xe-selective adsorbents, stimuli-responsive Xe/Kr-selective adsorbents still remain underdeveloped. Herein, a Hofmann-type framework Co(DABCO)[Ni(CN)(4)] (referred to as CoNi-DAB; DABCO = 1,4-diazabicyclo[2,2,2]octane) that provides a temperature-dependent switchable Xe/Kr separation performance is reported. CoNi-DAB showed high Kr/Xe (0.8/0.2) selectivity with significant Kr adsorption at 195 K as well as high Xe/Kr (0.2/0.8) selectivity with superior Xe adsorption at 298 K. Such adsorption features are associated with the temperature-dependent rotational configuration of the DABCO ligand, which affects the kinetic gate-opening temperature of Xe and Kr. The packing densities of Xe (2.886 g cm(-3) at 298 K) and Kr (2.399 g cm(-3) at 195 K) inside the framework are remarkable and comparable with those of liquid Xe (3.057 g cm(-3)) and liquid Kr (2.413 g cm(-3)), respectively. Breakthrough experiments confirm the temperature-dependent reverse separation performance of CoNi-DAB at 298 K under dry and wet (88% relative humidity) conditions and at 195 K under dry conditions. The unique adsorption behavior is also verified through van der Waals (vdW)-corrected density functional theory (DFT) calculations and nudged elastic band (NEB) simulations.
Keywords
SEPARATION; ADSORPTION; MOTION; metal-organic frameworks; rotational dynamics; thermoresponsive gating effect; xenon krypton separation
ISSN
1613-6810
URI
https://pubs.kist.re.kr/handle/201004/113471
DOI
10.1002/smll.202301905
Appears in Collections:
KIST Article > 2023
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