One Porous Metal–Organic Framework Containing Multinuclear Clusters and Functional Groups for Purification of Acetylene and Ethylene

For the critical yet challenging industrial processes of the selective removal of trace acetylene (C₂H₂) from ethylene (C₂H₄) and the separation of C₂H₂ from carbon dioxide (CO₂), we herein report the rational design and synthesis of a novel hydroxy-functionalized Zn(II)-based metal-organic framework, Zn-btb-OH, constructed from a custom-designed ligand, 1,3,5-tri(4-carboxyphenyl)benzene (H₃btb-OH). Zn-btb-OH features a unique interwoven architecture comprising open channels with flattened cage-like cavities and accessible -OH groups and demonstrates a high C₂H₂ adsorption capacity (60.1 cm³ g⁻¹ at 298 K and 100 kPa) and exhibits preferential adsorption for C₂H₂ over C₂H₄ and CO₂. Ideal Adsorbed Solution Theory (IAST) selectivity calculations reveal values of 2.2 and 4.4 for equimolar C₂H₂/C₂H₄ and C₂H₂/CO₂ mixtures at 298 K, respectively. Dynamic breakthrough experiments confirm its excellent practical separation performance, achieving the complete purification of C₂H₄ from C₂H₂ and efficient capture of C₂H₂ from CO₂. Grand Canonical Monte Carlo simulations elucidate that the superior affinity for C₂H₂ originates from multiple specific host-guest interactions, including C-H···π and C-H···O contacts.