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

Considering the small amount of CO 2 as a contaminant in industrial gas mixtures, developing CO 2 -selective adsorbents exhibit advantages in directly obtaining pure C 2 H 2 in one-step to reduce the energy consumption. However, it is still a great challenge due to the essential molecular feature of C 2 H 2 , including the triple bond and high polarizability. Herein, a simple but effective CO 2 -facilitated transport strategy is presented to realize the overwhelming adsorption of CO 2 over C 2 H 2 by constructing core–shell composite structures using ionic liquid (IL) and metal-organic framework (MOF). With the aid of excellent solubility of CO 2 in IL and almost total exclusion of C 2 H 2 , the obtained materials boost molecular sieving-based separation of CO 2 /C 2 H 2 . Density functional theory calculations combining molecular dynamic simulations revealed the solution-diffusion mechanism for CO 2 , which is rarely reported in solid adsorbents. Ideal adsorbed solution theory selectivity for CO 2 /C 2 H 2 with 1/1 and 1/3 volume ratios can reach over 10 4 and 4000 at 100 kPa with a high CO 2 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.