【作者】 林玉龙；

【导师】 魏雨； 贾振斌；

【作者基本信息】 河北师范大学 ， 物理化学， 2003， 硕士

【摘要】 纳米TiO₂微粒具有大的比表面积，其表面原子数、表面能和表面张力随粒径的下降急剧增加，由于其尺寸的细微化，表现出来的小尺寸效应，表面效应、量子尺寸效应及宏观量子隧道效应等特性导致纳米TiO₂微粒的热、光、敏感特性和表面稳定性等方面不同于常规粒子，这就使得它在环境、信息、材料、能源、医疗与卫生等领域有着广阔的应用前景。纳米TiO₂的附加值非常高，在近20年来引起工业发达国家的极大关注，并得到了蓬勃发展，其生产地区主要集中在西欧和北美，亚洲的日本与韩国也有较大的生产量，我国也进行了大规模的研究，有些企业已经进行了中试放大研究甚至规模化生产。纳米TiO₂粉体的工业化已经成为纳米材料科学研究的一个热点。 目前，全世界对纳米TiO₂粉体的制备问题进行了广泛的研究，得到的制备方法有很多，但是大部分只是局限于实验室阶段，适合工业化生产的方法相对较少。现在工业上纳米TiO₂的生产主要为气相法和液相法，其工艺或操作较复杂。气相法反应速度快，得到的纳米二氧化钛粉体纯度高、分散性好、团聚少、表面活性大，性能高，但是气相法反应是在高温下瞬间完成，要求反应物料在极短的时间内达到微观上的均匀混合，对反应器的型式、设备的材质、反应加热方式、进料方式均有很高的要求。目前，气相法在我国还处于小试阶段，欲达到工业化大规模生产，还需要解决一系列工程问题和设备材质问题；而液相法的原料来源广泛、成本较低、设备简单、便于大规模生产。其中以TiCl₄为原料进行液相研究的报道已有很多，但是它们的反应物浓度较低，反应时间较长，而且得到的产物形貌为类球形或针形，粒径分布较宽，需要高温煅烧才能得到晶化较好的纳米二氧化钛粉体。鉴于现有纳米TiO₂工业生产方法的优劣，我们实验室以TiCl₄为原料，采用沸腾回流强迫水解的液相方法进行纳米TiO₂的制备研究已经有几年了，此方法具有原料价廉易得、操作方便、反应条件温和的特点。在实验室小试阶段，我们可以控制反应产物的晶型、粒径与形貌，得到理想的产物。为了验证小试条件的放大效果和为进一步工业化生产提供理论和实践依据，我们进行了中试研究，这也是我论文的主要内容。 本论文详细研究了纳米二氧化钦制备条件的优化，考察了不同因素对产品结果的影响，并模拟工业化生产进行了整套工艺的研究，主要工作详述如下:（l）中试设备的选型与安装 根据生产工艺、纳米 TIO:的性质、中试规模、中试车间的空间及经济上的考虑，在借鉴同行业的实际情况，我们对所需设备进行了选型。我们所用设备的材质为不锈钢和塑料，选用内衬搪瓷的间歇反应釜作为反应器，无机陶瓷膜洗涤设备去除中试反应所得沉淀中的氯离子，采用沉降式离心机进行固液分离，利用闪蒸干燥设备对经过预烘干的物料进行干燥，得到粉体。根据中试需要，选择了一套纯水系统制备蒸馏水。将各设备安装后，进行了试车。（2）中试研究 对小试阶段的最佳反应条件进行了中试放大，放大规模为小试的1000倍，总反应体积为50L，CT*e，4=l.omol几，HZSO4为添加剂，CTicl4:CHZso4=40:1。此过程中系统研究了加料速率、升温速率及搅拌对产品晶型、粒径和形貌的影响。实验证明在控制一定温度的情况下，加料速率越快，对产品越有利;油浴加热，升温速率较慢，反应体系温度不均匀，改为提前预热到适当温度，缩短了升温时间，得到了较理想的结果;桨式搅拌的搅拌范围小，体系不均匀，改用锚式搅拌后，得到较均匀的球形纳米二氧化钦。 我们采用工业级TIC14为原料，反应体系中含有了大量的Cl一离子，由于Cl一离子的危害性，需要去除它。因为纳米TIO:的颗粒细小，一般的过滤方法容易出现穿滤或堵塞滤孔的问题，我们选用无机陶瓷膜洗涤设备将Cl一离子洗净。由于溶液的电导率与其离子的种类、浓度有关，通过描绘不同pH值下的电导率与cl一离子浓度的关系曲线，利用电导率仪监视渗透液的电导率，从而判断Cl一离子浓度的大小。在洗涤过程中利用0.01%AgNo3溶液辅助检验Cl一离子浓度。 闪蒸干燥是一种典型的气流干燥。利用热空气在料仓内进行涡流上升，从而带动经过输送轴粉碎的二氧化钦，相互摩擦，含水分少月颗粒小的颗粒_<sub>仁升到顶端，重的颗粒留在料仓继续干燥，最后得到粉体。通过控制加料口温度、出料口温度及出口风量，控制产品。实验证明，加料温度大于250℃为宜，出口风量最小较为合适。 经过闪蒸干燥的粉体，进一步锻烧可使粉体的水分减小，晶化更好。实验证明，400℃锻烧lh就可得理想产品，如温度过高，时间过长，则得到了混晶甚至金红石纯相。（3）纳米TIO:的主要特性指标及分析检验 作为一种产品，就要有其特性指标，这也是各行业的标准。纳米TIOZ的指标项目主要有纯度、晶型、比表面积、杂质含量、含水量、烧失重、pH、表观密度和团聚指数等。本论文对这些指标项目进行了总述，并且简要叙述了它们测定方法。（4）纳米二氧化钦晶体的表征 利用透射电子显微镜、X射线衍射仪、激光粒度分布仪、更多还原

【Abstract】 Recently, because special physics and chemistry properties of nanosized TiO₂ particles such as heat, light, sensitive properties and surface stability were quite different from general materials, they were intensively applied in the environment, information, material, sources of energy, medical treatment and hygiene etc. The surface atom number, surface ability and surface tension of nanosized TiO₂ particles with high surface area were sharply increased along with the degression of the diameter with high additional value, great concern and striking development were caused in industry-advanced countries over 20 years. Their production districts focus in Western Europe and the northern America, and another bigger output in Japan and Korea. A wide range of research has been carried out in our country, and some enterprises also have much effort in pilot studying and scope production. The industrialization of nanometer TiO₂ powder has become a hot aspect of nanometer material science research.At present, the preparation of nanometer TiO₂ powder has always been one of the most important subjects of research in the whole world. Lots of methods of preparation had been developed, but most of them restricted the industrial production. As far as we know, only gas and liquid phase methods can be applied in the industry in spite of complicated technology and operation. The nanometer TiO₂ powder from the gas method with fast rate has many characterists, such as higher purity, nice dispersity, little agglomeration, higher surface activity and high properties, As the gas reaction was accomplished temporarily at the high temperature, the mould type of reaction devices, material nature of equipment and the way of heatingand charge-in were highly required. Up to now, the gas method in our country is still under the experimental stage. In order to realize an industrial scale, a series of engineering and equipment problems have to be solved. While the liquid phase method has been developed to product on a large scale because of low cost, and simple equipment. Of all the reports, TiCl₄ often serve as a source of liquid phase research. But with lower reactant concentration and longer reaction time and high temperature calcinations, they can just achieve psendospherical or needle-type particles with broad size distribution. In view of the advantage and disadvantage of available methods of nanometer TiO₂ industry production, we prepared nanometer TiO₂ powder from TiCl₄ as the raw material through forced hydrolysis under the boiling reflux method in our laboratory over several years. The method has some outstanding characteristics, such as simple equipment, high initial concentration, short reaction time, low reaction temperature, uniform distribution of particle size etc. The morphology, size and crystal structure can be controlled. In order to verify the magnifying effect of experimental conditions and provide theory and practice basis to realize the industrialization, we make the pilot scale research.In this paper, I have studied the optimization of preparing condition of nanometer titania in detail, and investigated the influence of different factors to the resulting product, and imitated complete set technology of industrialization. The main research aspects are as follows: （1） Selecting and installing of equipmentAccording to the production technology, properties of nanometer TiO₂, capacity of the pilot scale experimental, the scope of work place and economical factors, we select the appropriate equipments in the workshop. We choose intermission vitreous enamel reactor as the reaction devices, use the inorganic ceramic membrane to wash the chlorine ion, use the sedimentation centrifuge to separate the solid and liquid phase, and utilizeflash vaporization drying equipment, we got the TiO₂ powder in the end. According to the basis needs, we have selected a set of pure water system to prepare the distilled water. After each equipment was installed, we had co更多还原