1998 Fiscal Year Final Research Report Summary
Catalytic Reactions of Metal Incorporated Silicon Clathrate Compounds
| Project/Area Number |
09640709
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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 |
物質変換
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
SHIOTANI Masaru Faculty of Applied Professor Engineering , Chemistry HIROSHIMA UNIVERSITY, 工学部, 教授 (80002137)
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| Co-Investigator(Kenkyū-buntansha) |
YAHIRO Hidenori Faculty of Applied Associate Professor Engineeing, Chemistry, Ehime University, 工学部, 助教授 (90200568)
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| Project Period (FY) |
1997 – 1998
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| Keywords | silicon clathrates / zeolites / metal incorporated / catalvtic reactions / ESR / electronic structure / molecular motion |
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| Research Abstract |
Some metal incorporated silicon claibrate and related compounds were newly synthesized and their electronic structures were investigated by means of magnetic resonance method, especially ESR, in order to develop a new type of micro-porous crystal catalysis. Furthermore, molecular motion of patamagnetic molecules adsorbed on metal ion exchanged zeolites was studied in order to get information about the relation between the molecular dynamics and catalytic activity in a typical micro-porous crystal. Two important results obtained are given below.
1. An ESR study was carried out for sodium-containing silicon clatbrate compounds, Na_xSi_1_3_6 with 3 <less than or equal> x <less than or equal> 10. For Na_3Si_1_3_6 the quartet with isotropic hf splitting of 13.3 mT was observed together with the weak septet of 6.7 mT at 4 K ; the former and later being attributed to Na atom and dimer cation of Na_2^+, respectively. The temperature dependent ESR spectral intensity of Na atom was observed in a
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wide temperature range from 4 K to 200 K.A deviation from the paramagnetic Curie's law was observed in higher temperature region and was discussed in terms of a thermal electron excitation from Na impurity level to the conduction band of the silicon clatbrate compound.
2. The molecular motion of adsorbed NO_2 was examined with ESR in several zeolites and analyzed using slow-motionsl EPR theory. In X- and Y-type zeolites the broadening of the spectra with temperature was analyzed by simulations using a rotational diffusion model. For the diffusion of NO_2 in Na-mordenite and Na-ZSM-5 the broadening of the spectra with increased temperature could be better simulated with the Heisenberg type of spin exchange model. The exchange was attributed to the interaction between NO_2 molecules diffusing along the zeolite channels. In Na-ZSM-5 the spin exchange rate increased rapidly with an increasing Si/Al ratio of the zeolite. The effect was attributed to the hindrance against diffusion by Na^+, the amount of which increases with a decreased Si/Al ratio. Less
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Research Products
(12 results)
