1998 Fiscal Year Final Research Report Summary
Correlation between Microscopic Structure and Chemical Reaction in Low-density Supercritical Water
| Project/Area Number |
09440207
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 | Fukuoka University |
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Principal Investigator |
YAMAGUCHI Toshio Fukuoka University, Faculty of Science, Prof., 理学部教授 (70158111)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Hydrogen-bonded cluster / Supercritical water / Supercritical methanol / Neutron diffraction / XAFS / Hydration structure / X-ray diffraction |
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| Research Abstract |
(1)High-temperature and high-pressure solution sample cells for XAFS, small-angle X-ray and neutron scattering have been constructed. Maximum pressure and temperature used for the cells are 50 MPa and 400 ﾟC.
(2)XAFS measurements on 0.1 M aqueous Co(N03)2 solution were made at 25ﾟC(0.1 MPa), 250ﾟC(30 MPa), and 400ﾟC(35 MPa). It has been found that the hydration number of Co^<2+> decreases from 6 at 25ﾟC to 4 at 400ﾟC, the Co-H_2 distance being 2.06-2.08 A.
(3)The structure of methanol at ambient (25ﾟC), subcritical (202ﾟC), and supercritical(253ﾟC)temperatures has been investIgated by neutron diffraction with hydroxyl H/D) substitution and Empiricat Parameter Structure Refinement methods. It has been found that methanol molecules are arranged as chain-like by hydrogen bonding and that clusters of 5-6 methanol molecules are formed at the supercritical temperature and are broken down with decreasing density.
(4)X-ray diffraction measurements on a methanol-water binary solution (methanol mole fraction is 0.3) were made over a temperature range 25-200ﾟC.It has been found that hydrogen bonds at 2.9 A are largely broken down with increasing non-hydrogen bonds at 3.5 A.
(5)The orientational correlation function on Cl hydration in supercritical water has been derived by neutron diffraction on a 3 m LiCl solution in D_2 with ^<35>C/^<37>C substitution, EPSR, and spherical harmonic expansion methods. It has been found that all water molecules around Cl remain in the first coordination shell, but are randomly oriented toward Cl.
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