A Self-Assembled Capsule for Propylene/Propane Separation

The development of energy-saving technology for the efficient separation of olefin and paraffin is highly important for the chemical industry. Herein, we report a self-assembled Fe4L6 capsule containing a hydrophobic cavity, which can be used to encapsulate and separate propylene/propane. The successful encapsulation of propylene and propane by the Fe4L6 cage in a water solution was documented by NMR spectroscopy. The binding constants K for the Fe4L6 cage toward propylene and propane were determined to be (5.0 +/- 0.1)x10(3 )M(-1) and (2.1 +/- 0.7)x10(4) M-1 in D2O at 25 degrees C, respectively. Experiments and theoretical studies revealed that the cage exhibited multiple weak interactions with propylene and propane. The polymer-grade propylene (> 99.5 %) can be obtained from a mixture of propylene and propane by using the Fe4L6 cage as a separation material in a U-shaped glass tube. This work provides a new strategy for the separation of olefin/ paraffin.