Precise Pore Engineering of Zirconium Metal-Organic Cages for One-Step Ethylene Purification from Ternary Mixtures

One-step purification of ethylene from ternary mixtures (C₂H₂, C₂H₄, and C₂H₆) can greatly reduce the energy consumption of the separation process, but it is extremely challenging. Herein, we use crystal engineering and reticular chemistry to introduce unsaturated bonds (ethynyl and alkyne) into ligands, and successfully design and synthesized two novel Zr-MOCs (ZrT-1-ethenyl and ZrT-1-alkyne). The introduction of carbon-carbon unsaturated bonds provides abundant adsorption sites within the framework while modulating the pore window size. Comprehensive characterization techniques including single crystal and powder X-ray diffraction, as well as electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) confirm that ZrT-1-ethenyl and ZrT-1-alkyne possess an isostructural framework with ZrT-1 and ZrT-1-Me, respectively. Adsorption isotherms and breakthrough experiments combined with theoretical calculations demonstrate that ZrT-1-ethenyl can effectively remove trace C₂H₂ and C₂H₆ in C₂H₄ and achieve separation of C₂H₂ from C₂H₄ and CO₂. ZrT-1-ethenyl can also directly purify C₂H₄ in liquid solutions. This work provides a benchmark for MOCs that one-step purification of ethylene from ternary mixtures.