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Water Sorption Cycle Measurements on Functionalized MIL-101Cr for Heat Transformation Application
Summary:
The authors from Universität Düsseldorf, Leuphana Universität Lüneburg, and Fraunhofer Institute for Solar Energy Systems ISE developed four functionalized MIL-101Cr materials with high water sorption capacity and cycle stability, achieving excellent performance in heat transformation applications.
Background:
1. To address the problems of low water loading, high desorption temperature, and poor cycle stability of traditional adsorbents (zeolites, silica gel), previous researchers explored MOFs as adsorbents, yet the water sorption performance at low humidity and long-term cycle stability needed improvement.
2. The authors proposed a time-controlled post-synthetic modification method, introducing amino/nitro groups into MIL-101Cr to obtain fully/partially functionalized materials, which enhanced low-humidity water sorption and cycle stability.
Research Content:
1.Synthesis: MIL-101Cr was synthesized via hydrothermal method; amino/nitro-functionalized (1, 3) and partially functionalized (2, 4) MIL-101Cr were prepared by nitration-reduction post-synthetic modification.
2.Characterizations:
1) BET: MIL-101Cr-NH₂ (1) had 2690 m²/g (40 cycles: 2520 m²/g), MIL-101Cr-pNO₂ (4) had 2195 m²/g (40 cycles: 1760 m²/g); total pore volumes were 1.60-0.70 cm³/g.
2) SEM: The materials maintained structural integrity after modification and cycles.
3) Other tests: PXRD confirmed framework retention; water sorption max. 1.06 g/g; adsorption heat 43-48 kJ/mol.
3.Application: Tested in 40 water adsorption-desorption cycles for heat transformation; 1 and 2 showed stable performance with low desorption temperature (55 °C).
4.Mechanism: Amino groups enhanced hydrophilicity and Cr-carboxylate bond stability; nitro groups’ electron-withdrawing effect weakened bond inertness, reducing cycle stability.
Outlook:
This research provides high-performance adsorbents for heat transformation, clarifies functional group effects on water sorption, and promotes MOF applications in energy-saving technologies.
Water Sorption Cycle Measurements on Functionalized MIL-101Cr for Heat Transformation Application
Authors: Anupam Khutia, Holger Urs Rammelberg, Thomas Schmidt, Stefan Henninger, Christoph Janiak
DOI: 10.1021/cm304055k
Link: https://pubs.acs.org/doi/10.1021/cm304055k
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