1998 Fiscal Year Final Research Report Summary
Control of Fine Structure of Group IVb and VB Metals By the Template Function of Silica and Invention of New Reaction Systems
| Project/Area Number |
09650904
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
工業物理化学
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| Research Institution | Kyoto Institute of Technology |
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Principal Investigator |
IMAMURA Seiichiro Kyoto Institute of Technology, Faculty of Engineering and Design, Professor, 工芸学部, 教授 (00027898)
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| Project Period (FY) |
1997 – 1998
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| Keywords | niobium / zirconium / silica matrix / coordination state / epoxidation / XAFS / ESR / titanium |
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| Research Abstract |
Ti, Zr, and Nb were incorporated into the silica tetrahedral matrix, and their coordination state was controlled with an aid of the template action of the silica.
XAFS analysis revealed that the Ti in titania-silica with low Ti content was in the tetrahedral (Td) environment and that in the high Ti content sample in the octahedral (Oh) environment. Td-Ti exhibited high activity to produce epoxide from oct-1-ene using t-butyl hydroperoxide as an oxidant. EPR spectra of superoxide oxide ion were observed by introducing oxygen on the surface of titania-silica. The g-value of the superoxide formed on Td-Ti was different from that on Oh-Ti and the effect of Ti content on these spectra was similar to that observed by the XAFS analysis. Thus XAFS technique well reflects the surface state of the titania-silica.
Zr and Nb incorporated into silica matrix with a small amount level also took Td-configuration and was active for epoxide formation. Thus, the liquid-phase epoxidation generally proceeds through the coordination of hydroperoxide to the coordinatively unsaturated metal ion in the first step of the reaction.
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