High-Flux High-Selectivity Metal-Organic Framework MIL-160 Membrane for Xylene Isomer Separation by Pervaporation...

摘要

Before its use as a critical feedstock, p-Xylene (PX), part of the BTX aromatics (benzene, toluene, and xylene isomers), must first be separated from o-xylene (OX), m-xylene (MX), and ethyl-benzene by distillation, adsorption, or crystallization. However, such techniques prove challenging concerning the separation of PX from OX and MX because of their similar molecular structures and close boiling points. Membrane-based separations have been explored as alternative strategies because of their low energy consumption, ease of operation, and cost-effectiveness. Metal-organic frameworks (MOFs) have attracted intense interest in the synthesis of molecular sieving membranes because of their highly diversified pore structures and sizes, as well as specific adsorption affinities. Herein, the authors describe the preparation of a continuous polycrystalline MIL-160 membrane ([AI(OH)(O2C-C4H2O-CO2)]) on a polydopamine (PDA)-modified Al2O3 support via an in situ solvothermal synthesis method. This membrane, with a pore size between 0.5 0.6 nm, is able to separate PX (0.58 nm) from the larger xylene isomers (OX and MX, 0.68 nm) (Figure 1).