Zeolite macrostructures

Abstract: The preparation of zeolite macrostructures in the form of bilayered hollow tubes and microspheres is presented. The bilayered hollow ZSM-5/silicalite-1 tubes were prepared using carbon fibers as a substrate. The surface of the fibers was modified and colloidal silicalite-1 seed crystals adsorbed. The fibers were then treated with a synthesis mixture yielding ZSM-5. After separation of the fiber/zeolite composites a second treatment resulting in the crystallization of silicalite-1 was performed. Finally, the carbon fibers were removed by calcination leaving hollow tubes. Silicalite-1 micropsheres were prepared using macroporous anion exchange resins as shape directing macro-templates. Resin beads were hydrothermally treated with a synthesis solution yielding silicalite-1 resulting in the crystallization of silicalite-1 in the pores of the resin. The resin was then removed by calcination leaving self-bonded silicalite-1 micropsheres identical in shape and size to the original resin beads. The zeolite macrostructures were extensively characterized using SEM, XRD, EDS-analysis, Raman spectroscopy, nitrogen adsorption and microhardness measurements.