Mechanochemical Synthesis of Cu(I)-MOF-74 for Improved Ethylene/Ethane Separation

A new metal-organic framework (MOF), i.e., Cu-(I)-MOF-74, is developed to selectively adsorb ethylene in ethylene-ethane gas mixtures. This new MOF is synthesized through the mechanochemical reaction between 2,5-dihydroxyterephthalic acid (DHTA) and cuprous oxide. The mechanochemical reactions between Cu₂O and DHTA at various ratios are investigated to determine the exact stoichiometry of the reaction. Using the XRD patterns of the synthesized MOF, we identified a 2:1 molar ratio of Cu₂O/DHTA as the correct reaction stoichiometry. The synthesized Cu-(I)-MOF-74 is stable up to 163 °C as evidenced by its thermogravimetric analysis, and has a 1371 m²/g BET surface area. Also, the adsorption isotherms of ethylene and ethane on this MOF are measured at 278, 298, 313, and 353 K. Finally, the isosteric heats of adsorption of ethylene and ethane on Cu-(I)-MOF-74 are calculated, and using the ideal adsorption solution theory (IAST), adsorption selectivities at the four above-mentioned temperatures are calculated.