An Ultramicroporous Metal–Organic Framework for High Sieving Separation of Propylene from Propane

Highly selective adsorptive separation of olefin/paraffin through porous materials can produce high purity olefins in a much more energy-efficient way than the traditional cryogenic distillation. Here we report an ultramicroporous cobalt gallate metal-organic framework (Co-gallate) for the highly selective sieving separation of propylene/propane at ambient conditions. This material possesses optimal pore structure for the exact confinement of propylene molecules while excluding the slightly large propane molecules, as clearly demonstrated in the neutron diffraction crystal structure of Co-gallate⊃0.38C₃D₆. Its high separation performance has been confirmed by the gas sorption isotherms and column breakthrough experiments to produce the high purity of propylene (97.7%) with a high dynamic separation productivity of 36.4 cm³ cm^-3 under ambient conditions. The gas adsorption measurement, pore size distribution, and crystallographic and modeling studies comprehensively support the high sieving C₃H₆/C₃H₈ separation in this MOF material. It is stable under different environments, providing its potential for the industrial propylene purification.