对撞流—旋转填料床反应器制备纳米硫酸钡工艺研究

【作者】 李军平；

【导师】 刘有智；

【作者基本信息】 华北工学院 ， 化学工艺， 2002， 硕士

【摘要】 本文研究了对撞流—旋转填料床反应器液相连续制备纳米硫酸钡新工艺。在系统分析纳米粒子形成热力学及动力学基础上，结合生成硫酸钡快速沉淀反应的特点，从理论上阐明了高度微观混合是液相法制备纳米硫酸钡的关键因素。 研究了对撞流—旋转填料床反应器的混合机制和速度分布，结果表明：对撞流—旋转填料床反应器能使两股液流在轴对称中心处形成一驻面薄层，在该层内速度梯度最大，可以实现高度微观混合；通过对比反应器的合成特性，研究了对撞流—旋转填料床反应器制备纳米硫酸钡的特性。 通过正交实验阐明了反应的操作参数转速是对撞流—旋转填料床反应器制备纳米硫酸钡的最为显著影响因素；通过优化实验考察了转速、流速等操作参数及体系温度、进料浓度对纳米硫酸钡粒径的影响规律，得到制备纳米硫酸钡最佳工艺条件：温度80℃、浓度1．Omol/L、转速800rpm、流量80L/h及反应物配比1：1。在此工艺条件下，可制备出粒径较小、分布较窄的纳米硫酸钡粒子。 并通过碟式离心实验表明：当分离因素达到9300时，纳米硫酸钡的分离效率为99．3％。分析探讨了纳米粒子在干燥过程中的团聚机理，喷雾干燥对比实验表明：在进行喷雾干燥前，添加极少量的表面活性剂D可以解决纳米粒子干燥过程中的团聚问题。最后对产品进行了XRD、BET及TEM表征分析，产品粒径为20-40nm。更多还原

【Abstract】 A new technology for continuous preparing nano barium sulfate in the impinging steam-rotating packed bed was studied. According to the analysis both of the synthesizing nano particles thermodynamics and dynamics. It was found theoretically that microcosrnic mixing thoroughly is a key factor in preparing nano barium sulfate based on the property of rapid reaction precipitation.Both mixing mechanism and velocity distribution in the impinging steam-rotating packed bed were investigated. As a result, a cyclical thin layer is formed in the center of impinging steam, There is the largest velocity grade that resulted in thorough microcosmic mixing. The characteristic of the impinging steam-rotating packed bed is discussed by means of comparing the property of two reactors.According to rhombic experiments, it was identified that rotating speed is the most important effect factor for preparing nano barium sulfate in the impinging steam-rotating packed bed. The effect of some technology parameters, such as rotating speed ,fluid flow, reaction temperature and reaction material concentration, on barium sulfate particles diameter were investigated experimentally.The optimum technology parameters were obtained based on the experiment, i.e. reaction temperature 80癈, reactive concentration 1.0mol/L,rotating speed 800rpm, inlet flow 80L/h and Ba2+1 SO2-4 = 1:1 .According to the experiments of centrifugal separation, the separation efficiency of nano barium sulfate in dish centrifugal separator reached99.3% when the centrifugal factor >9300.The agglomerate mechanism was discussed in drying process . Based on the experiments, it was found that the agglomeration of nano barium sulfate can be prevented by adding a little of surfactant in slurry before dried. The characteristics of nano barium sulfate was identified by means of XRD, BET and TEM. The average particle diameter is between 20 and 40nm .更多还原