Size-Exclusion Separation of Hexane Isomers by a Y-MOF Built on {Y(COO)₃} _n Chains

Due to the similar physicochemical properties, the separation of hexane isomers is a challenging task, but it is, however, of high importance in the petrochemical industry. In this study, we present a three-dimensional (3D) Y-based MOF, Y(BTB) (denoted as HIAM-318, H3BTB = 1,3,5-tri(4-carboxyphenyl)benzene), with a rarely reported bnn topology. HIAM-318 possesses one-dimensional (1D) channels with appropriate pore size, leading to size-exclusion-based separation of hexane isomers. It adsorbs linear n-hexane (nHEX) and monobranched 3-methylpentane (3MP) but can barely accommodate dibranched 2,2-dimethylbutane (22DMB). Multicomponent breakthrough experiments confirmed the separation capability. DFT calculations and computational modeling verified the size-sieving separation mechanism and revealed the domains of guest-host interactions.