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

Abstract

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)(H2 O)2 ],H2 dhbq = 2,5-dihydroxy-1,4-benzoquinone)is reported. The interchain space of the activated polymer is of optimal aperture size (5.58 Å) that could exclude 2,3-dimethylbutane, while the chain structure can discriminate n-hexane with high capacity (1.53mmol g-1 at 393 K, 6.67kPa) by high-density open metal sites (5.18mmol 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.