Silver-Decorated Hafnium Metal–Organic Framework\nfor Ethylene/Ethane Separation

Abstract

At\npresent, the dominant technology for olefin/paraffin separations\nis cryogenic distillation, which is extremely energy-intensive. Developing\nadvanced adsorbent materials would be a first step toward cost-effective\nalternatives such as pressure swing adsorption or temperature swing\nadsorption. In this work, we report a silver-decorated hafnium metal–organic\nframework, NUS-6­(Hf)-Ag, as a C₂H₄-selective\nadsorbent for C₂H₄/C₂H₆ separation. NUS-6­(Hf)-Ag was synthesized by the modulated hydrothermal\napproach followed by ion-exchange reactions. The successful introduction\nof Ag­(I), confirmed by X-ray photoelectron spectroscopy and energy-dispersive\nspectroscopy, increased the ideal C₂H₄/C₂H₆ selectivity of the resultant NUS-6­(Hf)-Ag material\nto 6, which was 5 times that of NUS-6­(Hf). Breakthrough experiments\nfurther confirmed the C₂H₄/C₂H₆ separation performance of NUS-6­(Hf)-Ag, indicating coadsorption\nC₂H₄/C₂H₆ selectivities\ngreater than 3. In addition, NUS-6­(Hf)-Ag was found to maintain its\ncrystallinity and the oxidation state of Ag­(I) after recyclability\ntests. This study clearly demonstrates the promising potential of\nAg-decorated metal–organic frameworks as adsorbent materials\nin adsorption-based C₂H₄/C₂H₆ separations.