Selective Acetylene Adsorption within an Imino-Functionalized Nanocage-Based Metal-Organic Framework

Removal of CH₄ and CO₂ from C₂H₂ streams remains challenging in the chemical industry. Herein, a robust three-dimensional metal-organic framework, Cu-CPAH, was designed and synthesized through a hydrothermal method. Cu-CPAH exhibits highly selective C₂H₂ adsorption capacity with respect to both CH₄ and CO₂, which is ascribed to the enrichment of active sites in the framework. Dynamic breakthrough results reveal that Cu-CPAH serves as a solid adsorbent for high-efficiency purification of C₂H₂ from an equal proportion of C₂H₂/CO₂ or C₂H₂/CO₂/CH₄ at room temperature. Discrete Fourier transform simulations confirm that various active sites preferentially interact with C₂H₂ other than CO₂ and CH₄, signifying for the first time that the imino functional groups in the cage contribute greatly to the preferential affinity to C₂H₂ over CO₂ and CH₄.