(630l) Sodalite ZIFs and Their Applications In Gas Adsorption and Separation

Zeolitic Imidazolate Frameworks (ZIF) have become a topic of intense research due to their microporous nature and crystallinity similar to zeolites.  ZIFs are attractive alternatives to traditional zeolite materials for several reasons.  They can be fabricated from a wide array of imidazole linkers, some of which can be functionalized.  This allows ZIF crystals to have finely-tuned pore sizes, which in turn, allows these structures to be tailored to a specific application due to micropore size and imidazole functionality. Moreover, the pore size in ZIFs tends be larger than that in zeolites with the same framework topology. This makes ZIF structures with sodalite topology attractive for the separation of hydrogen and other small gas molecules. ZIFs with sodalite topology lend themselves well to being grown into membranes for gas separations, and being produced in large quantities required for gas adsorption applications.  However, adsorption properties of sodalite ZIF structures have not been investigated systematically for several gas pairs important for energy-related separations. In this work, we investigated ZIF-7, -8,-9, -67, -90, and -91 made by conventional and microwave-assisted solvothermal synthesis and the following gas pairs: N₂/O₂, CO₂/N₂, H₂/CO₂, and H₂/CO. TGA and XRD were used to characterize the quality of each ZIF with respect to its crystallinity and completeness of solvent removal prior to adsorption studies.