One-Step Butadiene Purification in a Sulfonate-Functionalized Metal-Organic Framework through Synergistic Separation...

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.