A Zr-based metal-organic framework (MOF), UiO-66, is considered to be one of the most stable MOFs and has recently been shown to be a good candidate for adsorptive separation of Xe/Kr mixtures. Since the ability to impart chemical functionalities is an attractive characteristic of MOFs, herein, we prepared a series of functionalized UiO-66 materials (UiO-66-NH2, UiO-66-(OMe)2, UiO-66-NH2(OMe)2, and UiO-66-F4) by incorporating several polar functionalities into UiO-66. We found that series of electron-rich and electron-deficient UiO-66 materials have stronger interactions with Xe and Kr atoms than pristine UiO-66. We also found that Xe/Kr selectivity increases with the electron density of the ligand. Although there was a reduction in surface area, UiO-66-NH2(OMe)2 exhibited the highest Xe/Kr Henry's constant ratio (14.4), possibly due to having the highest electron density as well as an unsymmetrical arrangement of functional groups of the ligands. Furthermore, the breakthrough experiments show that UiO-66-NH2(OMe)2 can effectively separate Xe from Kr under dynamic mixture conditions and can be easily regenerated under a mild regeneration condition.
Bibliographical noteFunding Information:
This work was supported in part by the National Research Foundation of Korea under Grant ( NRF-2016R1A2B4014256 for S.-J.L. and Y.-S.B.; the Science Research Center NRF-2016R1A5A1009405 for S.K. and M.K.). This work was also supported by the National Institute of Supercomputing and Network/ Korea Institute of Science and Technology Information with supercomputing resources including technical support ( KSC-2015-C1-016 ). Appendix A
All Science Journal Classification (ASJC) codes
- Environmental Chemistry
- Chemical Engineering(all)
- Industrial and Manufacturing Engineering