Prof. Brad Chmelka, University of California at Santa Barbara Department of Chemical Engineering
January 26, 2012
11:00 AM - 12:00 PM
Self-assembly and Crystallization of Mesostructured Zeolites
Abstract:
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 mesoscopic and crystalline 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/reaction measurements, establish new molecular-level insights on the local interactions and distributions of complicated organic structure-directing agents with respect to crystallizing inorganic frameworks and their resulting catalytic reaction properties. The analyses reveal the formation of intermediate framework configurations, 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 the 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.
Date posted
Jun 17, 2019
Date updated
Jun 17, 2019