INTERNATIONAL COLLABORATION IN CHEMISTRY: Local structures of heteroatom environments and their effects on the reactivities of alumino-and borosilicates

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In this project, funded by the Experimental Physical Chemistry Program of the Division of Chemistry with support from the Office of International Science & Engineering, Professor Chmelka from University of California, Santa Barbara and his French collaborators from the Centre National de la Recherche Scientifique Laboratoire de Conditions Extrêmes et Matériaux in Orléans, seek to understand and control the molecular origins of the high activities and high selectivities of heteroatom-containing porous silicate and silica catalysts aimed at improving the energy efficiencies of chemical processes. The two groups have complementary expertises in catalyst synthesis, characterization, and spectroscopy method development. The main objectives of the project are:(i) to develop and apply new state-of-the-art methods of solid-state nuclear magnetic resonance (NMR) spectroscopy to establish the local compositions and structures at and near catalytically important aluminum and boron heteroatom moieties in nanoporous silicate and silica materials;(ii) to use the resulting insights to design and control heteroatom environments in porous silicate and silica frameworks to improve their macroscopic adsorption and reaction properties; and(iii) to educate and train students to provide strong fundamental understanding of state-of-the-art methods of NMR spectroscopy and syntheses, characterization, and properties of new catalytic materials.Local compositional and structural features, especially of framework aluminum and boron sites, are important, because they crucially influence the macroscopic adsorption and reaction properties of many catalytic materials, such as aluminosilicate zeolites that are responsible for nearly all of the world's current gasoline production. Despite their technological importance, much remains unknown at a molecular level about the origins of their activities, principally because of insufficient knowledge about the local environments at the Al and B active sites. Insights gained from solid-state NMR investigations will be correlated with macroscopic physicochemical (e.g., acidity, reactivity, adsorption) properties of the catalytic materials to obtain new molecular-level understanding of their complicated behaviors.Broader impacts of the project include the demonstration of new and general approaches for the measurement, understanding, design, and improvement of the local compositional and structural features that account for the reactivities of diverse classes of catalysts. Training of students in these areas is important, both nationally and internationally, and participation by students from underrepresented groups will be actively promoted. The collaborative and complementary efforts between the U.S. and French partners will provide cross-cultural and interdisciplinary research and education opportunities for students that will be broadly transferrable. It is expected that the insights gained from the proposed project will enable students and the broader scientific community to develop next-generation materials aimed at improving the energy-efficiency of processes and devices.