Fluorocarboxylic Acid-Modified MOF-808 with Enhanced Acetylene Adsorption Capacity and C2H2/C2H4 Separation Performance

Abstract

The separation of ethylene (C₂H₄) and acetylene (C₂H₂) is challenging due to their similar molecular dimensions and boiling points, making conventional methods like cryogenic distillation and solvent extraction inefficient and environmentally harmful. Fluorinated metal-organic frameworks (MOFs) have been proven to be an effective material for the separation of C₂H₄ and C₂H_2. However, their direct synthesis is relatively expensive and challenging. In this study, we report a facile post-synthetic modification strategy to introduce fluorinated alkane pores into a zirconium-based MOF, MOF-808. The construction of fluorine-containing pores within the MOFs prefers adsorption for C₂H₂ attributed to the interaction between the fluorine atoms and C₂H₂. This series of fluorinated MOFs demonstrates potential for gas separation processes, with the highest separation ratio reaching 2.67 (1 : 99) at 298 K. Breakthrough experiments for C₂H₂/C₂H₄ mixtures confirmed that fluorinated MOF is capable of separating C₂H₂/C₂H₄, making it a potential candidate for industrial application. Moreover, the simplicity of the post-synthetic modification method suggests a viable strategy for the synthesis of fluorinated MOFs.