Interaction-selective molecular sieving adsorbent for direct separation of ethylene from senary C2-C4 olefin/paraffin mixture.

Olefin/paraffin separations are among the most energy-intensive processes in the petrochemical industry, with ethylene being the most widely consumed chemical feedstock. Adsorptive separation utilizing molecular sieving adsorbents can optimize energy efficiency, whereas the size-exclusive mechanism alone cannot achieve multiple olefin/paraffin sieving in a single adsorbent. Herein, an unprecedented sieving adsorbent, BFFOUR-Cu-dpds (BFFOUR = BF₄^-, dpds = 4,4'-bipyridinedisulfide), is reported for simultaneous sieving of C₂-C₄ olefins from their corresponding paraffins. The interlayer spaces can be selectively opened through stronger guest-host interactions induced by unsaturated C = C bonds in olefins, as opposed to saturated paraffins. In equimolar six-component breakthrough experiments (C₂H₄/C₂H₆/C₃H₆/C₃H₈/n-C₄H₈/n-C₄H₁₀), BFFOUR-Cu-dpds can simultaneously divide olefins from paraffins in the first column, while high-purity ethylene (> 99.99%) can be directly obtained through the subsequent column using granular porous carbons. Moreover, gas-loaded single-crystal analysis, in-situ infrared spectroscopy measurements, and computational simulations demonstrate the accommodation patterns, interaction bonds, and energy pathways for olefin/paraffin separations. Olefin/paraffin separations are challenging in chemical industry. Here, authors report a sieving adsorbent for separating C2-C4 olefins from counterpart paraffins. The interlayer spaces are selectively opened via stronger guest-host interactions induced by olefins, as opposed to saturated paraffins. [ABSTRACT FROM AUTHOR]