INFRARED STUDY OF FLUID MIXTURES AT HIGH-TEMPERATURE AND HIGH-PRESSURE

本研究的目的是利用红外光谱研究水与苯、己烷等碳氢化合物的分子水平混合。【实验设置】高温高压红外电池按以下规格制作。电池本体材料：Nimonic Alloy 80A；工作压力/温度：1000bar / 400c；有效开口：6mm；总长度：100mm；加热器：电加热夹套；视窗材质：无色蓝宝石；试样的温度测量：热电偶。采用液相色谱注射泵将有机液体引入细胞并加压。[实验结果及总结]在温度373-573 K，压力1-400 bar范围内，测量了溶解在苯、己烷和环己烷中的H_2O和HDO的OH和OD拉伸红外吸收。在上述各烃类中，水的吸收强度随温度的升高而增加，这说明水溶性是如何增加的。在苯中，低温下的吸收主要集中在单体水分子上，但随着水溶性的增加，二聚体水的吸收带明显增加。这一事实表明，随着温度的升高，水的浓度迅速增加，质量作用的效果优于熵效应，熵效应倾向于单体而不是二聚体。在相同的温度和压力下，己烷和环己烷中的二聚体与单体的相对比大于苯中的二聚体与单体的相对比。这似乎与水在己烷和环己烷中的溶解度比在苯中的溶解度小有关。

The purpose of this study is to investigate molecular-level mixing of water with hydrocarbons such as benzene and hexane by infrared spectroscopy.[Experimental setup] the high-temperature and high-pressure infrared cell was made by the following specifications. Material of the cell body : Nimonic Alloy 80A ; working pressure/temperature : 1000 bar/400ﾟC ; Effective opening : 6 mm ; total length : 100 mm ; heater : electric heating jackets ; windows material : colorless sapphire ; temperature measurement of specimens : thermocouple. A syringe pump for liquid chromatography was used for introducing organic liquid into the cell and pressurising it.[Experimental results and summary] OH and OD stretching infrared absorptions of H_2O and HDO dissolved in benzene, hexane, and cyclohexane were measured at temperatures in the 373-573 K range and at pressures in the 1-400 bar range. In the every hydrocarbons mentioned above, absorption intensity of water increased with increasing temperature, which indicates how the water solubility increased. In benzene, the absorption at low temperature was mostly assigned to monomeric water molecules, but with the increase in water solubility a broad band assigned to dimeric water grew remarkably. This fact indicates that the effect of the mass action is superior to the entropy effect which prefer the monomer to the dimer, owing to the rapid increase in water concentration with increasing temperature. the relative ratio of the dimers to the monomers in hexane and cyclohexane was larger than that in benzene at the same temperature and pressure. This fact seems to be related to the fact that the water solubility in hexane and cyclohexane is smaller than in benzene.