Molecular Sieving of Propylene from Propane in Metal-Organic Framework-Derived Ultramicroporous Carbon Adsorbents

The development of adsorption-based separation processes alternative to the energy-intensive cryogenic distillation for a mixture of propylene and propane remains essential but challenging in gas industries. Molecular sieving separation of C₃H₆/C₃H₈ on stable carbon adsorbents appeals to be promising, while it is quite challenging to realize due to the random distributions and arrangements of the internal pores in common carbons. Herein, a series of polysaccharide-based CD-MOF-derived ultramicroporous carbon adsorbents with their pore size tuned at a subangstrom level were prepared. Molecular sieving separation of C₃H₆/C₃H₈ was realized on the optimal C-CDMOF-2-700 owing to the delicate structure with an appropriate pore size (5.0 Å). Besides, C-CDMOF-2-700 exhibited a high C₃H₆ uptake of 1.97 mmol g^-1 under ambient conditions. An ultrahigh uptake ratio of C₃H₆/C₃H₈ at 1.0 kPa (403) was also achieved, outperforming all reported adsorbents. Kinetic adsorption tests and breakthrough experiments further demonstrate this well-designed carbon adsorbent to be promising in industrial C₃H₆/C₃H₈ separation.