Accelerated C 2 H 2 /CO 2 Separation by a Se-Functionalized Porous Coordination Polymer with Low Binding Energy.

High-quality pure acetylene (C ₂ H ₂ ) is a kind of crucial starting material for various value-added products. However, selective capture of C ₂ H ₂ from the main impurity of CO ₂ 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 C ₂ H ₂ . 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 C ₂ H ₂ from the C ₂ H ₂ /CO ₂ mixture (1/4, v/v) at 298 K, along with higher C ₂ H ₂ 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 C ₂ H ₂ and CO ₂ 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 C ₂ H ₂ capture.