Van de Voorde Ben, Damasceno Borges Daiane, Vermoortele Frederik, Wouters Robin, Bozbiyik Belgin, Denayer Joeri, Taulelle Francis, Martineau Charlotte, Serre Christian, Maurin Guillaume, De Vos Dirk
Center for Surface Chemistry and Catalysis, KU Leuven, Arenbergpark 23, 3001 Leuven (Belgium).
Institut Charles Gerhardt, UMR CNRS 5253, UM ENSCM, Université de Montpellier, 34095 Montpellier Cedex 5 (France).
ChemSusChem. 2015 Sep 21;8(18):3159-66. doi: 10.1002/cssc.201500281.
The isolation and separation of phenolic compounds from aqueous backgrounds is challenging and will gain in importance as we become more dependent on phenolics from lignocellulose-derived bio-oil to meet our needs for aromatic compounds. Herein, we show that highly stable and hydrophobic Zr metal-organic frameworks of the MIL-140 type are effective adsorbent materials for the separation of different phenolics and far outperform other classes of porous solids (silica, zeolites, carbons). The mechanism of the hydroquinone-catechol separation on MIL-140C was studied in detail by combining experimental results with computational techniques. Although the differences in adsorption enthalpy between catechol and hydroquinone are negligible, the selective uptake of catechol in MIL-140C is explained by its dense π-π stacking in the pores. The interplay of enthalpic and entropic effects allowed separation of a complex, five-compound phenol mixture through breakthrough over a MIL-140C column. Unlike many other metal-organic frameworks, MIL-140C is remarkably stable and maintained structure, porosity and performance after five adsorption-desorption cycles.
从水性体系中分离和提纯酚类化合物具有挑战性，并且随着我们越来越依赖木质纤维素衍生生物油中的酚类物质来满足对芳香族化合物的需求，这一挑战将变得愈发重要。在此，我们展示了高度稳定且疏水的MIL-140型锆基金属有机框架材料是分离不同酚类物质的有效吸附剂，其性能远超其他类多孔固体材料（二氧化硅、沸石、碳）。通过将实验结果与计算技术相结合，详细研究了对苯二酚 - 邻苯二酚在MIL-140C上的分离机理。尽管邻苯二酚和对苯二酚之间的吸附焓差异可忽略不计，但MIL-140C对邻苯二酚的选择性吸附可归因于其在孔道内形成的密集π-π堆积。焓效应和熵效应的相互作用使得通过MIL-140C柱的穿透实现了一种复杂的五组分酚类混合物的分离。与许多其他金属有机框架不同，MIL-140C非常稳定，在经过五次吸附 - 解吸循环后仍保持结构、孔隙率和性能。
