Separation of xylene isomers in an adaptable metal-organic framework.
basic_science · Level V
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- Record sourced from PubMed, PMID 42600023.
- Also identified by DOI 10.1126/sciadv.aeg1691.
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Abstract
Efficient separation of xylene isomers by adsorption remains challenging due to insufficient selectivity arising from their molecular similarity. We report an adaptable metal-organic framework, Ni(BIC)<sub>2</sub> [1-<i>H</i>-benzimidazole-5-carboxylic acid (HBIC)], that exhibits high selectivity for <i>para</i>-xylene over other xylene isomers. Ni(BIC)<sub>2</sub> features a guest-adaptive one-dimensional channel that precisely matches the molecular projection dimensions of <i>para</i>-xylene, enabling sieving from a quaternary mixture of xylene isomers. The structural transformation of Ni(BIC)<sub>2</sub> upon guest adsorption substantially widens the disparity in binding energies between <i>para</i>-xylene and its counterparts. Weakly adsorbed components are converted into nonadsorbed entities, leading to temperature-independent <i>para</i>-xylene uptake while excluding <i>meta</i>-xylene and <i>ortho</i>-xylene. Breakthrough experiments demonstrate remarkable dynamic selectivity, delivering high-purity <i>para</i>-xylene within a single fixed-bed adsorption process. Simulated moving bed (SMB) process analysis demonstrates that Ni(BIC)<sub>2</sub> delivers a 3.2-fold increase in production efficiency relative to conventional zeolite under milder operating conditions.