One‐Step Butadiene Purification in a Sulfonate‐Functionalized Metal‐Organic Framework through Synergistic Separation Mechanism

Porous materials that could recognize specific molecules from complex mixtures are of great potential in improving the current energy‐intensive multistep separation processes. However, due to the highly similar structures and properties of the mixtures, the design of desired porous materials remains challenging. Herein, a sulfonate‐functionalized metal‐organic framework ZU‐609 with suitable pore size and pore chemistry is designed for 1,3‐butadiene (C4H6) purification from complex C4 mixtures. The sulfonate anions decorated in the channel achieve selective recognition of C4H6 from other C4 olefins with subtle polarity differences through C‐H···O‐S interactions, affording recorded C4H6/trans‐2‐C4H8 selectivity (4.4). Meanwhile, the shrunken mouth of the channel with a suitable pore size (4.6 Å) exhibits exclusion effect to the larger molecules cis‐2‐C4H8, iso‐C4H8, n‐C4H10 and iso‐C4H10. Benefiting from the moderate C4 olefins binding affinity exhibited by sulfonate anions, the adsorbed C4H6 could be easily regenerated near ambient conditions. Polymer‐grade 1,3‐butadiene (99.5%) is firstly obtained from 7‐component C4 mixtures via one adsorption‐desorption cycle. The work demonstrates the great potential of synergistic recognition of size‐sieving and thermodynamically equilibrium in dealing with complex mixtures.