Sequential Separation of Linear, Mono-, and Di-Branched Hexane Isomers on a Robust Coordination Polymer with Nonbonding Flexibility

Efficient separation of hexane isomers is a crucial process for upgrading gasoline. Herein, the sequential separation of linear, mono-, and di-branched hexane isomers by a robust stacked 1D coordination polymer termed as Mn-dhbq ([Mn(dhbq)(H2O)(2)], H(2)dhbq = 2,5-dihydroxy-1,4-benzoquinone) is reported. The interchain space of the activated polymer is of optimal aperture size (5.58 angstrom) that could exclude 2,3-dimethylbutane, while the chain structure can discriminate n-hexane with high capacity (1.53 mmol g(-1) at 393 K, 6.67 kPa) by high-density open metal sites (5.18 mmol g(-1)). With the temperature- and adsorbate-dependent swelling of interchain spaces, the affinity between 3-methylpentane and Mn-dhbq can be deliberately controlled from sorption to exclusion, and thus a complete separation of ternary mixture can be achieved. Column breakthrough experiments confirm the excellent separation performance of Mn-dhbq. The ultrahigh stability and easy scalability further highlight the application prospect of Mn-dhbq for separation of hexane isomers.

Automated summary

The sequential separation of linear, mono-, and di-branched hexane isomers using a robust stacked 1D coordination polymer named Mn-dhbq is reported. The activated polymer has an optimal aperture size in the interchain space that can exclude 2,3-dimethylbutane, while the chain structure can differentiate n-hexane. By controlling the swelling of interchain spaces, the affinity between 3-methylpentane and Mn-dhbq can be deliberately changed, achieving a complete separation of a ternary mixture.