【作者】 王艳；

【导师】 陆小华；

【作者基本信息】 南京工业大学 ， 工业催化， 2006， 硕士

【摘要】 水热法发展至今已经近两百年的历史,被广泛地应用于生长各种单晶、制备功能陶瓷粉体、完成某些有机反应或对一些危害人类生存环境的有机废弃物进行处理,以及在相对较低的温度下完成对某些陶瓷材料的烧结等。然而,由于水热过程发生于密闭的容器中,反应的压强较高,高耐受性的反应釜材质和对高压釜进行良好密封成为水热反应的先决条件。同时,苛刻的反应条件给各项参数的测量也带来了困难,人们只能通过对反应物的检测来调整参数,这样的处理使得水热反应长期被视为一个“黑箱”,影响了水热法的工业发展。安全问题以及反应机理的局限性是阻碍水热法应用的关键因素,明确反应釜内的压强和离子真实浓度是解决安全问题以及更进一步研究水热反应机理的必要前提,从而提出建立压强与填充度关系的热力学模型的构想。本文在同时考虑水化和缔合作用的基础上,建立了水热反应条件下NaOH、KOH水溶液的活度系数计算的热力学模型。为了满足热力学上的一致性,分别采用水的活度和溶质的平均活度系数对模型参数进行了回归,并将模型中的参数拟合成温度和压力的函数。对NaOH水溶液在323.15~523.15K、1.013~400bar以及KOH在348.15~573.15K、1.013~85.879bar的研究表明,该模型的预测结果是可靠的。将本文的活度系数模型与水热反应釜中的质量守衡和相平衡方程相联立,建立了水热条件下NaOH、KOH水溶液的填充度模型,预测了水热条件下的压强、反应釜中液相体积以及溶液中真实离子浓度随温度、溶液浓度和填充度的变化关系曲线。与纯水体系相比,相同反应温度、初始填充度下,NaOH和KOH水溶液产生的压强显著降低:250℃时,填充度为90%的纯水产生的压强为1367bar,而10mol·kg-1的NaOH溶液产生的压强仅为111.6bar;液相线上压强随温度急剧升高,而在汽液平衡线上压强的变化则相对平缓;相同初始浓度,不同初始填充度的溶液在相同反应温度下所产生的压强不同,并且随着浓度的增加和反应温度的升高,各填充度的下的压强差异更加明显。体积的变化曲线能够预测反应釜中液相高度随温度的变化情况,从而推断各反应温度下,液相充满整个反应釜时所对更多还原

【Abstract】 Hydrothermal technology has a history of two hundred years. Today, hydrothermal technology is widely applied to grow of various single crystals, preparation of ceramic powder, deal with organic pollution, produce nano-materials, and so on.The pressure in autoclaves is very high because the hydrothermal reactions occur in a closed system. So it should be rugged enough to bear high pressure and temperature experiments for long duration. When selecting a suitable autoclave, the first and foremost parameter is the experimental temperature and pressure conditions and the corrosion resistance in the pressure-temperature range in a given solvent or hydrothermal fluid. At the same time, the extreme condition makes it difficult to measure the parameters. The“black box”nature of the hydrothermal system hinders the development of the hydrothermal industry. In this thesis, the safety and limitation of the mechanism are thought to the key factor in handicap the application of hydrothermal technology. Determination of the pressure and the real concentration is the precondition of solving the safety problem and the further study of the mechanism of hydrothermal reaction. Consequently, the idea of building a thermodynamics model that relates pressure and initial filling factor is raised.In this thesis, both hydration and association effects are taken into account to build an activity coefficient model of aqueous NaOH and KOH solution under hydrothermal conditions. In order to satisfy the consistency of thermodynamics, the parameters of this model are regressed by activities of water and mean activity coefficients of solutes and fitted as the function of temperature and pressure. The research on NaOH at 323.15~523.15K, 1.013~400bar and KOH at 348.15~573.15K、1.013~85.879bar show that the predicted values are reliable.The model proposed in this paper is combined with phase equilibria and mass balance to build the model of filling factor to predict the pressure, liquid volume in the vessel and real concentration of ions.更多还原