超临界水理论研究的进展

Recent Progress in Supercritical Water Theoretical Research

通过计算模拟、拉曼光谱、NMR以及衍射分析对超临界水静态结构进行了广泛的研究 ,氢键结构是这些研究的重要内容。研究结果显示在临界点附近水的氢键结构受到了很大的破坏 ,只有相当于常温下 2 9%左右的氢键存在。利用微波波谱法、NMR法以及准弹性不连续中子散射方法对超临界水动力学进行了研究。结果发现 ,在临界点附近 ,水分子的动力学重排时间急剧缩短 ,这就使得以超临界水为介质的化学反应速率大大增加。由于微波的周期比较长 ,可能大大地超过了超临界水结构的动力学重排时间 ,因此微波波谱法不适合于高温低密度超临界水的动力学研究。

Simulative computation, Raman spectroscopy, NMR and diffraction are the important methods to study the static structures of supercritical water. The results show that the hydrogen bond of supercritical water near critical region is only 29% of that of ambient condition. Microwave spectrum NMR and quasielastic incoherent neutron scattering methods are adopted to study the dynamics of supercritical water. The results indicate that the time of rearrangement decreases greatly near critical region, which account for the increase of reaction rate in supercritical water. This is the basis for study of the mechanism of reaction rate in supercritical water. The microwave spectrum method is not appropriate for supercritical water at high temperature and low density conditons because the period of microwave is longer than the period of rearrangement. The experimental and simulative studies of mechanism and dynamics of hydrogen bond in supercritical water are the main research areas in the near future.