2005 Fiscal Year Final Research Report Summary
Effect of Diffusion on Reaction Dynamics in Sub- and Supercritical Fluids
| Project/Area Number |
16550023
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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 |
Physical chemistry
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| Research Institution | Doshisha University |
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Principal Investigator |
IBUKI Kazuyasu Doshisha University, Faculty of Engineering, Professor, 工学部, 教授 (30201940)
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| Co-Investigator(Kenkyū-buntansha) |
UENO Masakatsu Doshisha University, Faculty of Engineering, Professor, 工学部, 教授 (50121588)
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| Project Period (FY) |
2004 – 2005
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| Keywords | Supercritical Fluid / Subcritical Condition / Diffusion / Electric Conductivity / Diffusion-Controlled Reaction / Computer Simulation |
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| Research Abstract |
In order to investigate the diffusion process and its effect on the reaction dynamics in sub- and supercritical fluids, we carried out the following research.
The first subject is the electric conductivity measurements of monovalent ions in subcritical methanol and ethanol in the temperature range 60-240℃ along the liquid-vapor coexistence curve. The results were discussed with a special attention to the density effect. For the alkali metal and the halide ions, the conductivities increased with deceasing density from the ambient one down to the density two times as large as the critical one. These results agreed with the predictions of the dielectric friction theory based on the sphere-in-continuum model. At lower densities, however, the experimental conductivities decreased significantly ; this tendency was in the opposite direction to the continuum theory. This clearly indicates that the application range of the sphere-in-continuum model is that higher than that two times as large as
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the critical one. For the tetraalkyl-ammonium ions, we could perform the measurements only up to 160℃. For the large tetrapropyl- and tetra-butylammonium ions, the experimental and the theoretical conductivities agreed well. For the small tetra-methyl- and tetraethylammonium ions, large discrepancies were observed between them. This might be attributed to the effect of the hydrogen-bonded structure of the solvent alcohols.
The second subject is the computer simulations of diffusion-controlled reactions in supercritical Lennard-Jones and rigid-sphere fluids. For a better understanding of the reaction dynamics in sub- and supercritical fluids, it is necessary to examine the density effect over a wide range. These fluids are suitable for this purpose. We found that the theory based on the Fokker-Planck equation explained the reaction dynamics observed by the simulations in the whole density range. This indicates that the inertia effect on he molecular motions plays an important role in determining the reaction dynamics at medium and low densities. Less
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