Accelerated C₂H₂/CO₂ Separation by a Se-Functionalized Porous Coordination Polymer with Low Binding Energy

High-quality pure acetylene (C₂H₂) is a kind of crucial starting material for various value-added products. However, selective capture of C₂H₂ from the main impurity of CO₂ via porous absorbents is a great challenge, as they possess extremely similar kinetic diameters and boiling points, as well as the explosive and reactive properties of C₂H₂. Herein, we report a porous coordination polymer (PCP), (NTU-55), which assembled from the coordination between a Cu dimer and a newly designed ligand with a nonmetal selenium (Se) site. Static single-component adsorption and dynamic breakthrough experiments reveal that desolvated NTU-55 can completely adsorb C₂H₂ from the C₂H₂/CO₂ mixture (1/4, v/v) at 298 K, along with higher C₂H₂ capacity and much lower binding energy. The origin of this separation, as comprehensively revealed by density functional theory (DFT) calculations, is derived from the interaction discriminatory of C₂H₂ and CO₂ toward accessible Se and Cu adsorption sites. To the best of our knowledge, this is the first time to find the positive effect of nonmetal Se sites for selective C₂H₂ capture.