(266e) Development of Molecular and Mesoscopic Order In Mesostructured Zeolites | AIChE

(266e) Development of Molecular and Mesoscopic Order In Mesostructured Zeolites


Messinger, R. J. - Presenter, University of California
Na, K. - Presenter, Korea Advanced Institute of Science and Technology

Mesoporous zeolites represent a new and technologically important class of materials that exhibit improved transport, catalytic, and adsorption properties compared to conventional zeolites with sub-nanometer pore dimensions.  During their syntheses, the transient development(s) of crystalline and mesoscopic order are closely coupled and difficult to control.  Such processes are important to monitor and understand to optimize the compositions, structures, and properties of mesostructured zeolites. In particular, solid-state nuclear magnetic resonance (NMR) spectroscopy, in conjunction with small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and adsorption measurements, establish new molecular-level insights on the local interactions and distributions of complicated organic structure-directing agents with respect to crystallizing inorganic frameworks.  The analyses reveal the formation of intermediate layered frameworks, which subsequently transform into zeolitic structures with novel combinations of both nano- and mesoscale porosities.  Such materials are shown to result from competition between simultaneous and coupled surfactant self-assembly and inorganic crystallization processes, the interplay between which governs the onset and development of framework structural order on different length scales. The results provide criteria for rational design strategies aimed at synthesizing hierarchically porous zeolites with different framework morphologies and improved transport, catalytic, and adsorption properties.