(253f) Hybrid of Metal-Organic Framework and Ionic Liquid As Adsorbent for Adsorptive Separation of Acetylene and Ethylene

During the process of petroleum and natural gas cracking to produce ethylene, one of the most industrially important raw chemicals, a small amount of acetylene (C₂H₂) as a by-product of about 1% is unavoidably generated, and will take serious detriment during the process of producing polyethylene. The commercial methods of removing C₂H₂ from C₂H₄ include partial hydrogenation and solvent extraction are costly, energy-intensive, and have several drawbacks. As an outstanding alternative for gas separation, MOFs, as well as functionalized MOFs by post-synthetic modification, have been tentatively utilized for removal of C₂H₂ from C₂H₄, but the adjustability of adsorption capacity and selectivity is not flexible enough to satisfy different demands from chemical industries. Therefore, Ionic liquids (ILs) catch our attention due to their unique properties, such as high thermal and chemical stability, negligible vapor pressures and high designability as a result of nearly unlimited number of possible combinations of different anion-cation pairs.

Herein, we first reported an IL@MOF composite by incorporating ILs into a mesoporous MOF material for efficient separation of C₂H₂ and C₂H₄. It was well established that the selectivity of C₂H₂/C₂H₄ was greatly improved from 3.0 to 9.6 through the encapsulation of IL, at the meantime it maintained an adequate adsorption capacity for C₂H₂. Furthermore, the potential of industrial practice was examined by breakthrough and regeneration experiments. It not only satisfies the industrial production of removal of low level of acetylene from ethylene, but also is notably stable during the adsorption-desorption process. The high designability of ILs combined with richness of MOFs’ structures exploits a novel blueprint for gas separation.