Pore-Architecture-Guided Dense Packing in Uniform Channels with V-Shaped Confinement for Energy-Efficient Separation of Hexane Isomers

Abstract

The separation of C6 alkane isomers is a critical yet energy-intensive step in high-octane gasoline production, owing to their similar molecular sizes and boiling points. Herein, we report a pore-architecture-guided strategy for continuous C6 isomer separation by constructing a metal–organic framework, ZJU-Bao-291, featuring uniform V-shaped channels that enable exceptionally dense molecular packing. The periodic V-shaped confinement units impose precise size exclusion on dibranched 2,2-dimethylbutane (22DMB), while simultaneously promoting ultrahigh adsorption densities for the nontarget linear and monobranched isomers, n-hexane (n-Hex) and 3-methylpentane (3MP), through spatial isolation of adjacent guest molecules. As a result, both isomers achieve record pore-volume-normalized loadings (LNPV), representing the highest packing efficiencies reported to date among MOF-based C6 separation materials. Static adsorption measurements, multicomponent breakthrough experiments, and molecular simulations collectively elucidate the adsorption, packing, and transport behavior within the V-shaped channels. Enabled by the exceptional capture capacity and robustness of ZJU-Bao-291, vapor-phase simulated moving bed (V-SMB) simulations demonstrate continuous enrichment of 22DMB with ultrahigh purity (>99.95%) at only one-fifth of the energy consumption required by conventional distillation. This work establishes pore-architecture-guided molecular packing as an effective principle for designing adsorbents for energy-efficient continuous hydrocarbon separations.