Solubility‐Boosted Molecular Sieving‐Based Separation for Purification of Acetylene in Core–Shell IL@MOF Composites

Abstract Considering the small amount of CO₂ as a contaminant in industrial gas mixtures, developing CO₂‐selective adsorbents exhibit advantages in directly obtaining pure C₂H₂ in one‐step to reduce the energy consumption. However, it is still a great challenge due to the essential molecular feature of C₂H₂, including the triple bond and high polarizability. Herein, a simple but effective CO₂‐facilitated transport strategy is presented to realize the overwhelming adsorption of CO₂ over C₂H₂ by constructing core–shell composite structures using ionic liquid (IL) and metal‐organic framework (MOF). With the aid of excellent solubility of CO₂ in IL and almost total exclusion of C₂H₂, the obtained materials boost molecular sieving‐based separation of CO₂/C₂H₂. Density functional theory calculations combining molecular dynamic simulations revealed the solution‐diffusion mechanism for CO₂, which is rarely reported in solid adsorbents. Ideal adsorbed solution theory selectivity for CO₂/C₂H₂ with 1/1 and 1/3 volume ratios can reach over 10⁴ and 4000 at 100 kPa with a high CO₂ uptake of 40.3 cm³ g⁻¹, superior to those of the reported materials so far. More importantly, this solution‐based separation strategy can avoid the difficulty for precise control of the regulation of adsorbent structure, which may be beneficial to practical production.