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

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 10(4) and 4000 at 100 kPa with a high CO2 uptake of 40.3 cm(3) 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.