Developing Design Criteria and Scale Up Methods for Water-Stable Metal-Organic Frameworks for Adsorption Applications.

摘要

Metal-organic frameworks (MOFs) are a relatively new class of porous materials, assembled from inorganic metal nodes and organic ligands. MOFs have garnered significant attention in the porous materials and adsorption field in recent years due to their various attractive features such as high surface areas and pore volumes, uniform pore sizes which are easily tunable, chemically functionalized adsorption sites, and potential for post-synthetic modification (PSM). These features give MOFs enormous potential for use in applications such as air purification, gas storage, adsorption separations, catalysis, gas sensing, and drug delivery. Therefore, synthesis and adsorption studies of porous MOFs have increased tremendously in recent years. Among the aforementioned applications, air purification and air quality control are important topics because existing porous media are ineffective at the adsorptive removal of toxic industrial chemicals (TICs) and chemical warfare agents (CWAs). Thus, there is a critical need for radical improvements in these purification systems. MOFs have shown great potential to become next-generation filter media as they outperform the traditional porous materials such as activated carbons and zeolites in the air purification of TICs such as ammonia and sulfur dioxide. In spite of the numerous desirable attributes of MOFs, the practical use of these new materials in applications ranging from adsorption separations to controlled storage and release hinges on their stability in humid or aqueous environments. The sensitivity of certain MOFs under humid conditions is well known, but systematic studies of water adsorption properties of MOFs are scarce. This information is critical for identifying structural factors that are important for the development of next-generation, water stable metal-organic frameworks. In addition to the water stability issue, difficulty in the scaleup of MOF synthesis has also plagued MOFs.