Efficient Propylene/Ethylene Separation in Highly Porous Metal-Organic Frameworks.

Light olefins are important raw materials in the petrochemical industry for the production of many chemical products. In the past few years, remarkable progress has been made in the synthesis of light olefins (C2-C4) from methanol or syngas. The separation of light olefins by porous materials is, therefore, an intriguing research topic. In this work, single-component ethylene (CH) and propylene (CH) gas adsorption and binary CH/CH (1:9) gas breakthrough experiments have been performed for three highly porous isostructural metal-organic frameworks (MOFs) denoted as FeM-L (M = Mn, Co, or Ni), three representative MOFs, namely ZIF-8 (also known as MAF-4), MIL-101(Cr), and HKUST-1, as well as an activated carbon (activated coconut charcoal, SUPELCO). Single-component gas adsorption studies reveal that FeM-L, HKUST-1, and activated carbon show much higher CH adsorption capacities than MIL-101(Cr) and ZIF-8, HKUST-1 and activated carbon have relatively high CH/CH adsorption selectivity, and the CH and CH adsorption heats of FeMn-L, MIL-101(Cr), and ZIF-8 are relatively low. Binary gas breakthrough experiments indicate all the adsorbents selectively adsorb CH from CH/CH mixture to produce purified CH, and 842, 515, 504, 271, and 181 cm g CH could be obtained for each breakthrough tests for HKUST-1, activated carbon, FeMn-L, MIL-101(Cr), and ZIF-8, respectively. It is worth noting that CH and CH desorption dynamics of FeMn-L are clearly faster than that of HKUST-1 or activated carbon, suggesting that FeM-L are promising adsorbents for CH/CH separation with low energy penalty in regeneration.