Separation of Xylene Isomers through Multiple Metal Site Interactions in Metal–Organic Frameworks,Journal of the American Chemical Society

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Separation of Xylene Isomers through Multiple Metal Site Interactions in Metal–Organic Frameworks
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2018-02-15 , DOI: 10.1021/jacs.7b13825
Miguel I Gonzalez , Matthew T Kapelewski , Eric D Bloch , Phillip J Milner , Douglas A Reed , Matthew R Hudson ₁ , Jarad A Mason , Gokhan Barin , Craig M Brown _{1,

2} , Jeffrey R Long ₃

Affiliation

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. Herein, 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.

中文翻译：

通过金属有机框架中多个金属位点相互作用分离二甲苯异构体

C8 烷基芳烃邻二甲苯、间二甲苯、对二甲苯和乙苯的纯化仍然是最具挑战性的工业分离之一，因为这些分子具有相似的形状、沸点和极性。在此，我们报告了金属有机骨架 Co2(dobdc) (dobdc4- = 2,5-dioxydo-1,4-苯二甲酸) 和 Co2( m-dobdc) ( m-dobdc4- = 4,6-dioxydo) 的评估-1,3-苯二甲酸）用于使用单组分吸附等温线和多组分突破测量分离二甲苯异构体。值得注意的是，Co2(dobdc) 在所有四个分子中都有所区别，其结合亲和力遵循邻二甲苯 > 乙苯 > 间二甲苯 > 对二甲苯的趋势。多组分液相吸附测量进一步证明 Co2(dobdc) 在很宽的浓度范围内保持这种选择性。单晶 X 射线衍射的结构表征表明，两种框架都通过每个 C8 客体分子与两个相邻钴 (II) 中心之间的相互作用程度以及每个异构体填充在框架孔内的能力来促进分离。此外，与假定的 M2(dobdc) 结构刚性相反，Co2(dobdc) 在邻二甲苯或乙苯存在下表现出意想不到的结构变形，从而能够容纳额外的客体分子。

更新日期：2018-02-15

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