(731a) Synthesis and Characterization of Nanocrystalline Zeolites for Catalysis

Nanocrystalline zeolites, beta and ZSM-5, with hierarchical porosity were synthesized in one step from single template systems.  By systematically tuning the reaction conditions, such as the concentration of the reacting species, temperature, synthesis duration and pH, the formation of isolated nanocrystals or mesoporous aggregates of zeolites beta and ZSM-5 was achieved. Depending on the synthesis conditions, zeolite nanocrystals of approximately 20 to 150 nm in diameter or mesoporous aggregates of approximately 100 to 200 nm in diameter were prepared. The zeolites were characterized by electron microscopy, solid state NMR, nitrogen adsorption and powder x-ray diffraction. The crystallinity of the samples determined from pXRD patterns is similar to that of commercially available micron-sized zeolites.  The ability to systematically control the zeolite morphology has important implications for catalysis.