Direct Ethylene Purification from Cracking Gas via a Metal-Organic Framework Through Pore Geometry Fitting

The direct one-step separation of polymer-grade C₂H₄ from complex light hydrocarbon mixtures has high industrial significance but is very challenging. Herein, an ethylene-adsorption-weakening strategy is applied for precise regulation of the pore geometry of four tailor-made metal-organic frameworks (MOFs) with pillar-layered structures, dubbed TYUT-10/11/12/13. Based on its pore geometry design and functional group regulation, TYUT-12 exhibits exceptional selective adsorption selectivity toward C₃H₈, C₃H₆, C₂H₆, C₂H₂, and CO₂ over C₂H₄; its C₂H₆/C₂H₄ adsorption selectivity reaches 4.56, surpassing the record value of 4.4 by Fe₂(O₂)(dobdc) (dobdc^4- = 2,5-dioxido-1,4-benzenedicarboxylate). The weak pi-pi stacking binding affinity toward C₂H₄ in TYUT-12 is clearly demonstrated through a combination of neutron powder diffraction measurements and theoretical calculations. Breakthrough experiments demonstrate that C₂H₄ can be directly obtained from binary, ternary, quaternary, and six-component light hydrocarbon mixtures with over 99.95% purity.