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Correlation between Microscopic Structure and Chemical Reaction in Low-density Supercritical Water

低密度超临界水微观结构与化学反应的相关性

基本信息

批准号：
09440207
负责人：
YAMAGUCHI Toshio
金额：
$ 5.31万
依托单位：
Fukuoka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

(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.

（1）建立了用于XAFS、小角X射线和中子散射的高温高压溶液样品池。电池使用的最大压力和温度为50 MPa和400 ℃。（2）在25 ℃（0.1MPa）、250 ℃（30 MPa）和400 ℃（35 MPa）下对0.1M Co（NO3）2水溶液进行了XAFS测量。发现Co^<2+>的水化数从25 ℃时的6下降到400 ℃时的4，Co-H_2距离为2.06-2.08 A。（3）用羟基取代中子衍射和经验参数结构精修方法研究了甲醇在常温（25 ℃）、亚临界（202 ℃）和超临界（253 ℃）下的结构。发现甲醇分子通过氢键成链状排列，在超临界温度下形成5-6个甲醇分子的团簇，并随着密度的降低而分解。（4）在25-200 ℃温度范围内对甲醇-水二元溶液（甲醇摩尔分数为0.3）进行了X射线衍射测量，发现在2.9A处的氢键大部分被破坏，而在3.5A处的非氢键增加。（5）用3 mLiCl在D_2中的溶液的中子衍射，用^ C/^ C取代、EPSR和球谐展开方法，导出了Cl在超临界水中水合的取向关联函数<35><37>。已经发现，Cl周围的所有水分子保持在第一配位壳层中，但是随机地朝向Cl取向。