Incorporation of Multiple Binding Sites into an Adaptive MOF for Sieving Butane Isomers.

Efficient separation of liner alkanes from branched alkanes is of prime importance in the petrochemical industry. Herein an adaptive metal‐organic framework <bold>FJI‐H38</bold> is reported with 1D channel which can vary delicately ≈4.0 Å. The activated <bold>FJI‐H38</bold> displays extremely large butane (<italic>n‐</italic>C4H10) capacity, especially at low pressure (44.15 cm3 g−1 at 298 K and 0.1 bar), but barely adsorbs isobutane (<italic>i</italic>so‐C4H10). Remarkably, <bold>FJI‐H38</bold> possesses a high <italic>n‐</italic>C4H10/<italic>iso‐</italic>C4H10 selectivity of 246.75. Gas‐loaded single crystal X‐ray analysis and modeling calculation reveal that the synergetic effect of pore confinement and surfaces decorated with uncoordinated carboxyl group plays a critical role in the capture of the relatively smaller <italic>n‐</italic>C4H10 while the exclusion of the larger <italic>iso‐</italic>C4H10. In addition, dynamic breakthrough tests explicitly prove <bold>FJI‐H38</bold> displays prominent separation performance for <italic>n</italic>/<italic>iso‐</italic>C4H10 under various conditions with ultra‐high productivity of high‐purity <italic>n‐</italic>C4H10 (42.48 L/kg, ≥99.0%) and <italic>iso‐</italic>C4H10 (42.35 L/kg, ≥99.95%). [ABSTRACT FROM AUTHOR]