Abstract:
Metal-organic frameworks (MOFs) hold immense promise in membrane-based gas separation and pervaporation due to their precisely tunable pore structures and the vast library of available MOF compounds (exceeding 10,000 structures). Despite more than a decade of advancements in pure MOF membrane development, only a handful have achieved exceptional separation performance. This presentation explores recent breakthroughs from our research group, focusing on elucidating the mechanisms of molecular transport within MOF membranes. First, understanding the free energy profiles of adsorbate molecules is critical for unraveling their adsorption and diffusion behaviors in MOFs. I will demonstrate how these profiles can be determined through a synergistic approach combining simulations and experimental data. Our research highlights the importance of uniformly adsorptive surfaces within MOF channels, and I will provide practical examples to show how such homogeneous and robust adsorption surfaces significantly enhance the separation efficiency of MOF membranes. Next, I will discuss our recent discovery of the unique "knock-off" mechanism that governs water transport in UTSA-280 membranes. This mechanism imparts remarkable water/ethanol selectivity in membrane pervaporation, opening new avenues for applications. Finally, I will present our latest findings on single-file diffusion in MOF membranes with one-dimensional channels. This mechanism represents a paradigm shift in gas separation performance, transitioning from diffusion-dominated processes to those driven by adsorption. Through these insights, we aim to advance the design and application of MOF membranes for more efficient and selective separation processes.