The development of adsorption-based separation processes alternative to the energy-intensive cryogenic distillation for the mixture of propylene (C3H6) and propane (C3H8) remains essential but challenging in the gas industries. Molecular sieving separation of C3H6/C3H8 mixture 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 ultramicroporous carbon adsorbents C-CDMOF-2-T (T=500-700 Celsius) with the pore size tuned at sub-angstrom level was prepared by direct pyrolysis using polysaccharide-based CD-MOFs as precursors. 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 relatively high C3H6 uptake of up to 1.97 mmol g-1 at 298 K and 1.0 bar combined with a low zero-coverage adsorption heat of 34.6 kJ mol-1. Ultrahigh uptake ratio (403) of C3H6/C3H8 at 1.0 kPa was also achieved, outperforming all reported adsorbents. Kinetic adsorption tests and breakthrough experiments further demonstrate this well-designed carbon adsorbent as a promising candidate for industrial C3H6/C3H8 separation.

Molecular sieving of propylene from propane in metal-organicframework-derived ultramicroporous carbon adsorbents

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ACS Fall 2022

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