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 (C(2)H(4)) and propylene (C(3)H(6)) gas adsorption and binary C(3)H(6)/C(2)H(4) (1:9) gas breakthrough experiments have been performed for three highly porous isostructural metal–organic frameworks (MOFs) denoted as Fe(2)M-L (M = Mn(2+), Co(2+), or Ni(2+)), 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 Fe(2)M-L, HKUST-1, and activated carbon show much higher C(3)H(6) adsorption capacities than MIL-101(Cr) and ZIF-8, HKUST-1 and activated carbon have relatively high C(3)H(6)/C(2)H(4) adsorption selectivity, and the C(2)H(4) and C(3)H(6) adsorption heats of Fe(2)Mn-L, MIL-101(Cr), and ZIF-8 are relatively low. Binary gas breakthrough experiments indicate all the adsorbents selectively adsorb C(3)H(6) from C(3)H(6)/C(2)H(4) mixture to produce purified C(2)H(4), and 842, 515, 504, 271, and 181 cm(3) g(−1) C(2)H(4) could be obtained for each breakthrough tests for HKUST-1, activated carbon, Fe(2)Mn-L, MIL-101(Cr), and ZIF-8, respectively. It is worth noting that C(3)H(6) and C(2)H(4) desorption dynamics of Fe(2)Mn-L are clearly faster than that of HKUST-1 or activated carbon, suggesting that Fe(2)M-L are promising adsorbents for C(3)H(6)/C(2)H(4) separation with low energy penalty in regeneration.