Guest-molecule-induced self-adaptive pore engineering facilitates purification of ethylene from ternary mixture

Purification of ethylene from multicomponent mixtures is progressing toward one-step separation by a single material at room temperature and atmospheric pressure. However, conventional rigid porous materials cannot efficiently separate ethylene with a size close to acetylene and ethane through pore sieving. Herein, we report a cobalt metal-organic framework, UPC-66, that exhibits a self-adaptive pore structure under an external stimulus. In situ powder X-ray diffraction confirmed that the pore size of activated UPC-66-a can undergo synchronous dynamic transformation with temperature, pressure, and guest molecules. Dynamic breakthrough experiments show that the polymer-grade C2H4 can be obtained from a C2H2/C2H4/C2H6 (1/1/1 and 1/98/1) ternary mixture. The corresponding productivity of C2H4 can reach 2.01 mmol/g. The specific separation performance is attributed to the privileged adsorption sites of the self-adaptive pores, determined by the single-crystal data after gas encapsulation. This work provides valuable guidance for the application of self-adaptive pore structures in multicomponent separations.