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Updated: Aug 1, 2025
Synthesis and Characterization of Functionalized Metal-organic Frameworks
Published on: September 5, 2014
Switchable Xe/Kr Selectivity in a Hofmann-Type Metal-Organic Framework via Temperature-Responsive Rotational Dynamics
Hyojin Kim1, Jong Hyeak Choe1, Minjung Kang1
1Department of Chemistry, Korea University, Seoul, 02841, Republic of Korea.
A novel Hofmann-type framework, CoNi-DAB, demonstrates temperature-switchable selectivity for krypton (Kr) and xenon (Xe) separation. This adsorbent offers efficient Kr adsorption at 195 K and Xe adsorption at 298 K, crucial for industrial applications.
Area of Science:
- Materials Science
- Chemical Engineering
- Adsorption Science
Background:
- Efficient separation of krypton (Kr) and xenon (Xe) is critical for industrial processes and energy conservation.
- Existing Xe-selective adsorbents often lack stimuli-responsive properties, limiting their application flexibility.
- Development of adsorbents with tunable selectivity for Kr/Xe mixtures is an ongoing research challenge.
Purpose of the Study:
- To develop a stimuli-responsive adsorbent for switchable Kr/Xe separation.
- To investigate the temperature-dependent adsorption behavior of a Hofmann-type framework.
- To explore the potential of Co(DABCO)[Ni(CN)4] (CoNi-DAB) for selective Kr and Xe capture.
Main Methods:
- Synthesis and characterization of the Hofmann-type framework Co(DABCO)[Ni(CN)4] (CoNi-DAB).
- Gas adsorption isotherms measurement at different temperatures (195 K and 298 K).
- Breakthrough experiments under various humidity conditions.
- Computational studies including van der Waals (vdW)-corrected density functional theory (DFT) and nudged elastic band (NEB) simulations.
Main Results:
- CoNi-DAB exhibits temperature-dependent selective adsorption: high Kr/Xe selectivity at 195 K and Xe/Kr selectivity at 298 K.
- Remarkable packing densities of Xe and Kr within the framework, comparable to their liquid states.
- Demonstrated stable, reversible, and temperature-switchable separation performance under dry and humid conditions.
Conclusions:
- The Hofmann-type framework CoNi-DAB presents a unique temperature-responsive platform for switchable Kr/Xe separation.
- The observed adsorption behavior is attributed to the temperature-modulated rotational dynamics of the DABCO ligand.
- CoNi-DAB shows significant potential for advanced gas separation applications requiring tunable selectivity.
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