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

(1)建立了XAFS、小角X射线和中子散射的高温高压溶液样品室。电池的最大压力和温度分别为50ﾟ和400ﾟC。(2)0.1M Co(N03)2水溶液分别在25ﾟC(0.1 Mpa)、250ﾟC(30 Mpa)和400 MbC(35 Mpa)下进行了XAFS测量。结果表明，Co^&lt；2+&gt；的水化数从25ﾟC时的6降到400ﾟC时的4，Co-H_2距离为2.06-2.08。(3)用中子衍射法和Empiricat参数结构修正方法研究了甲醇在常温(25ﾟC)、亚临界(202ﾟC)和超临界(253ﾟC)温度下的结构。(4)在25-200ﾟC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2.9A的氢键大部分被破坏，3.5A的非氢键增加。(5)用X-射线衍射法计算了超临界水中氯水合的取向关联函数。中子在3m氯化锂溶液中的衍射；35&gt；C/^&lt；37&gt；C代换、EPSR和球谐展开方法。研究发现，氯周围的所有水分子都保持在第一配位壳层中，但无规地朝向氯。

(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.