Engineering pore limiting diameter of metal-organic frameworks for benchmark separation of mono- and di-branched hexane isomers

The separation of mono- and di-branched hexane isomers remains an important and challenging industrial process for the production of high-octane gasoline. Suitable adsorbents with high adsorption selectivity and capacity are urgently required. Herein, we demonstrate a strategy to realize highly efficient kinetically controlled hexane isomers adsorption separation that utilizes the tunability of the pore limiting diameter in M2TTFTB (M=Zn, Mn, Cd) by metal substitution. The appropriate refinement of the partially contracted pore not only improved the kinetic selectivities, but also enhanced the host-guest interaction and increased the adsorption capacity of 3MP and nHEX. The resulting Mn2TTFTB brought about both the record capacity of 3MP and the record kinetic selectivities of 3MP/22DMB and nHEX/22DMB, exhibiting the largest productivity of high-purity 22DMB in the breakthrough experiments, which sets a new benchmark for the hexane isomers separation via a rarely reported kinetically controlled mechanism.