Shape-based sieving of hexane isomers in liquid-phase by a scalable metal–organic framework

The separation of mono- and di-branched alkane isomers is an industrially important yet highly challenging process requiring precise pore structures. Here, we report a scalable metal–organic framework, Ni 3 (H 1.5 BTC) 2 (BTC)(DABCO) 3 (denoted as Ni-HDB), featuring an anisotropic, “bat-shaped” pore window that enables precise discrimination of the sterically similar 3-methylpentane (3MP) and 2,3-dimethylbutane (23DMB) pair (~0.3 Å difference in kinetic diameter), thereby enabling efficient separation of mono- and di-branched isomers. Multicomponent vapor- and liquid-phase experiments, supported by molecular simulations, reveal that separation arises from shape-governed molecular accommodation rather than simple size exclusion. Notably, under industrially relevant liquid-phase conditions, a packed column of pelleted Ni-HDB directly produces a high-octane gasoline fraction (RON > 91.5) from a five-component alkane mixture, substantially exceeding the industrial benchmark of 83 for refined hexane mixtures. Combined with scalable synthesis, high stability, and low cost, this work establishes a practical, energy-efficient route for liquid-phase adsorptive upgrading of branched alkanes.