Flexible Layered Metal-Organic Framework for Temperature-Dependent Discrimination of Cyclic Hydrocarbons

The separation and purification of cyclic hydrocarbons such as benzene, cyclohexene, and cyclohexane represent a crucially important but challenging process in the petrochemical industry. In this study, we show a flexible two-dimensional metal-organic framework (MOF) acting as an efficient adsorbent for the adsorptive separation of C6 cyclic hydrocarbons via molecular-sieving. The 2D-MOF features fully reversible structure transformation upon the removal/recoordination of terminal H2O and solvent DMF, and between activated and hydrocarbon-loaded forms. The distinct temperature- and adsorbate-dependent adsorption behavior is accompanied by guest-induced expansion of the layered structure. Such behavior enables the full discrimination of the individual C6 cyclic hydrocarbons from their binary and ternary mixtures by temperature-programmed protocols, achieving the third and second highest uptake ratios for C6H6/C6H12 and C6H10/C6H12 among MOFs reported to date. This study represents the first example of using a flexible 2D layered MOF sorbent to separate ternary mixtures of C6 cyclic hydrocarbons via a temperature-dependent molecular-sieving mechanism.