Separation of Xylene Isomers through Multiple Metal Site Interactions in Metal–Organic Frameworks
Journal Article
·
· Journal of the American Chemical Society
- Univ. of California, Berkeley, CA (United States)
- Univ. of California, Berkeley, CA (United States); Univ. of Delaware, Newark, DE (United States)
- National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States)
- Univ. of California, Berkeley, CA (United States); Harvard Univ., Cambridge, MA (United States)
- National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Univ. of Delaware, Newark, DE (United States)
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Materials Sciences Division; Univ. of California, Berkeley, CA (United States)
Purification of the C8 alkylaromatics o-xylene, m-xylene, p-xylene, and ethylbenzene remains among the most challenging industrial separations, due to the similar shapes, boiling points, and polarities of these molecules. We report the evaluation of the metal-organic frameworks Co2(dobdc) (dobdc4- = 2,5-dioxido-1,4-benzenedicarboxylate) and Co2( m-dobdc) ( m-dobdc4- = 4,6-dioxido-1,3-benzenedicarboxylate) for the separation of xylene isomers using single-component adsorption isotherms and multicomponent breakthrough measurements. Remarkably, Co2(dobdc) distinguishes among all four molecules, with binding affinities that follow the trend o-xylene > ethylbenzene > m-xylene > p-xylene. Multicomponent liquid-phase adsorption measurements further demonstrate that Co2(dobdc) maintains this selectivity over a wide range of concentrations. Structural characterization by single-crystal X-ray diffraction reveals that both frameworks facilitate the separation through the extent of interaction between each C8 guest molecule with two adjacent cobalt(II) centers, as well as the ability of each isomer to pack within the framework pores. Moreover, counter to the presumed rigidity of the M2(dobdc) structure, Co2(dobdc) exhibits an unexpected structural distortion in the presence of either o-xylene or ethylbenzene that enables the accommodation of additional guest molecules.
- Research Organization:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF); National Institutes of Health (NIH)
- Grant/Contract Number:
- AC02-05CH11231; SC0001015; AC02-06CH11357
- OSTI ID:
- 1974037
- Alternate ID(s):
- OSTI ID: 1460856
- Journal Information:
- Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 9 Vol. 140; ISSN 0002-7863
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Atomic‐ and Molecular‐Level Design of Functional Metal–Organic Frameworks (MOFs) and Derivatives for Energy and Environmental Applications
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journal | August 2019 |
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