Efficient olefin/paraffin separation is a grand challenge because of their similar molecular sizes and physical properties, and is also a priority in the modern chemical industry. Membrane separation technology has been demonstrated as a promising technology owing to its low energy consumption, mild operation conditions, tunability of membrane materials, as well as the integration of physical and chemical mechanisms. In this work, inspired by the physical mechanism of mass transport in channel proteins and the chemical mechanism of mass transport in carrier proteins, recent progress in channel-based and carrier-based membranes toward olefin/paraffin separations is summarized. Further, channel-based membranes are categorized into membranes with network structures and with framework structures according to the morphology of channels. The separation mechanisms, separation performance, and membrane stability in channel-based and carrier-based membranes are elaborated. Future perspectives toward membrane-based olefin/paraffin separation are proposed.

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Covalent organic framework (COF) membranes with tunable ordered channels and free organic groups hold great promise in molecular separations owing to the synergy of physical and chemical microenvironments. Herein, we develop a defect engineering strategy to fabricate COF membranes for efficient CO 2 separation. Abundant amino groups are in situ generated on the COF nanosheets arising from the missing-linker defects during the reactive assembly of amine monomer and mixed aldehyde monomers. The COF nanosheets are assembled to fabricate COF membranes. Amino groups, as the CO 2 facilitated transport carriers, along with ordered channels endow COF membrane with high CO 2 permeances exceeding 300 GPU and excellent separation selectivity of 80 for CO 2 /N 2 , and 54 for CO 2 /CH 4 mixed gas under humidified state. Our defect engineering strategy offers a facile approach to generating free organic functional groups in COF membranes and other organic framework membranes for diverse chemical separations.