期刊
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
卷 21, 期 35, 页码 19529-19537出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/c9cp04099d
关键词
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资金
- U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences
- DOE [DE-AC02-07CH11358]
- Australian Research Council [DP150103842, DP180104010]
- SOAR Fellowship
- Energy and Materials Clusters
- Early Career Research Scheme from the University of Sydney
- Major Equipment Scheme from the University of Sydney
- Faculty's MCR Scheme
In spite of the widespread applications of amorphous silica-aluminas (ASAs) in many important industrial chemical processes, their high-resolution structures have remained largely elusive. Specifically, the lack of long-range ordering in ASA precludes the use of diffraction methods while NMR spectroscopy has been limited by low sensitivity. Here, we use conventional as well as DNP-enhanced Si-29-Si-29, Al-27-Al-27, and Si-29-Al-27 solid-state NMR experiments to shed light on the ordering of atoms in ASAs prepared by flame-spray-pyrolysis. These experiments, in conjunction with a novel Monte Carlo-based approach to simulating RESPDOR dephasing curves, revealed that ASA materials obey Loewenstein's rule of aluminum avoidance. 3D O-17{H-1} and 2D O-17{H-1,Al-27} experiments were developed to measure site-specific O-H and HO-Al distances, and show that the Bronsted acid sites originate predominantly from the pseudo-bridging silanol groups.
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