| 题名 | 四氯化钛高温气相氧化法制备钛白粉的基础研究 |
| 作者 | 王志 |
| 学位类别 | 博士 |
| 答辩日期 | 2004 |
| 授予单位 | 中国科学院过程工程研究所 |
| 授予地点 | 中国科学院过程工程研究所 |
| 导师 | 袁章福 |
| 关键词 | 氯化法 钦白 合成 产品性能 结疤 |
| 其他题名 | Study on Preparation of Titania Particles from TiCl_4 by Vapor Phase Oxidation Route |
| 学位专业 | 化学工艺 |
| 中文摘要 | 四氯化钦高温气相氧化法制备钦白粉的基础研究钦白粉是重要的精细化工产品，广泛应用于涂料（60％）、塑料（16％）、造纸（14％）、油墨（3％）、化纤、橡胶等（7％）工业部门。我国的高档金红石型钦白几乎全部依赖进口，且进口量逐年增加。氯化法钦白的核心是Ticl4气相氧化反应过程。本项目基于我国唯一的氯化法铁白产品性能（颗粒粒度及分布、晶型转化率、消色力等）几乎不可控、氧化过程连续运转周期短的现状，对氧化过程进行机理研究和过程优化，为解决高档钦白生产中的难题，提升我国钦白工业的竞争能力奠定基础。本文建立了TiCl4气相氧化法制备钦白粉的实验装置，液体TiCl4通过蒸发后与干燥的氧气在石英反应器内决速反应，反应器最高温度可达1200℃1反应停留时间控制在1．005内。本文主要内容包括：（1）四氯化钦气相氧化反应机理研究对Ti-Al-Cl-O四元系的相关热力学进行了计算，模拟工业反应器的操作条件，计算分析了AIC13发生器和氧化反应器内可能发生的各种反应，得到了反应条件对TIC14及AlCl3平衡转化率的影响规律，证实晶型转化剂的平衡产物以Al2O3·TiO2固溶体为主，且其平衡转化率在1300℃以上随着温度的升高迅速降低。采用作图法和最小二乘法研究了TiCl4氧化过程的宏观动力学，求得了氧化过程的动力学方程并考察了反应温度和TiCl4流量对反应速率的影响。实验中通过改变反应参数，采用奥式气体分析仪检测尾气的成分，求得了氧化反应的动力学参数。两种方法得到的表观活化能分别为97．39kJ／ln01和80．01kJ／mol，频率因子分别为1.0487*104s-1和2.09*102mg／Pa2·min。（2）气相氧化过程工艺操作条件的优化采用TEM，SEM，PSD，XRD和EDS等实验手段研究氧化反应温度制度（初始预热温度、反应温度）、初始反应物料的混合比例、反应停留时间、强制冷却、晶型转化剂等对认白粉颗粒尺寸、形貌及品型的影响；研究了晶型转化剂AlCl3在氧化过程中的屏f型转化机理；初步得到了控制钦白颗粒尺寸及晶型含量的技术原型。（3）四氯化钦气相氧化反应器结疤机理的研究研究了工业反应器结疤的形貌特征，分析了其结疤机制。发现工业氯化法钦白氧化反应器壁内结疤物基本由堆结层、板结层和烧结层构成；颗粒堆结层主要为金红石型，烧结层为锐钦型。另外，研究了不同反应区的结疤特征并提出预防反应器结疤的对策。实验室结疤过程的研究表明，反应区前端的结疤为结构致密的薄膜，而反应区后端的结疤为发生烧结的粗大颗粒，反应器不同位置的结疤符合成膜和成核机制。反应器内射流TiCl4的低穿透率引起其附壁效应加强和大尺度逆流气团的形成，是造成氧化反应器内结疤的原因。从改变射流TiCl4的流体力学性质和加强反应器壁温降等方面提出了预防结疤生成的思路。 |
| 英文摘要 | Titanium dioxide is one of the most utilized particulate materials in the world, such as pigment (60%), plastic (16%), paper making (14%), printing ink (3%), chemical fiber and rubber (7%). China imports tens of tons of rutile titania annually and this presents an increase trend. The TiCU oxidation is the key part in the chloride process, which is the more cost effective and cleaner route. The phase content and grain size of titanium dioxide often have a strong influence on properties for a variety of applications, however, the relative importance of these synthesis variables on the grain size and phase content of TiO2 is not well understood and it is not in control in China. In addition, as key equipment in chloride process, the oxidation reactor scaling problem is difficult to deal with and it is the main reason for production halts. Based on the above backgrounds, the following works to resolve the existing problems have been conducted. A vapor phase route for preparation of titanium dioxide particles by oxidation of gaseous titanium tetrachloride has been established. The liquid titanium tetrachloride is vaporized and interacts with hot oxygen to form pigmentary titanium dioxide and generate chlorine. Reactor temperatures up to 1200 °C were used with residence time in the range of 1.00 s. The main parts in this paper are as follows: (1) The thermodynamics related to Ti-Al-Cl-0 system has been studied. Based on the industry operation conditions, the reactions happened in the AICI3 reactor and the oxidation reactor are analyzed, and the rates of conversion of TiCLi and AICI3 at different conditions are calculated. The results showed that the product of crystal transformer was mainly of solid solution Al2O3-TiO2, and the rate of conversion of AICI3 decreased swiftly above 1300 °C. The oxidation kinetics of titanium tetrachloride to produce titanium dioxide is studied to get an understanding of the TiCl4 oxidation reaction. The kinetics equations have been got through graphing method and least square method, and the parameters influencing on the oxidation rate has been studied. By varying the reactor temperature, the inlet concentration of TiCU, and the flow rate of the gases, and measuring the outlet concentration via Orsat gas apparatus, the kinetic constants were calculated. Assuming first order kinetics with respect to TiCU and using the Arrhenius law to model the rate constant, the activation energy and pre-exponential factor calculated were 97.39 kJ/mol and 1.0487*1 OV1 by the former method, while 80.01 kJ/mol and2.09><102mg/Pa2-min when determined by the latter method. (2) The TEM, SEM5 PSD, XRD, and EDS determined the morphology and grain size and phase content. In this study, analysis was used to determine the relative effects of reactor temperature, oxygen temperature, oxygen flow rate, titanium precursor (chloride) and dopants on grain size and crystalline phase content. It is showed that the morphology and the phase structure of T1O2 particles can be controlled through adjustment of reactor temperature, concentration of TiCU, primary oxygen fraction and the gas velocity. As a result, the optimum parameters favoring improving products properties have been concluded. (3) The SEM results showed that the laminar scaling block in industry reactor is consisted of packed layer, hardened layer and sintered layer. Analysis by XRD indicated the packed layer is mainly rutile TiO2 and the sintered layer anatase TiC>2. The detailed scaling process showed that the scale in front (S-F) is made of thin and hard film, while the scale in rear (S-R) is made of sintered particle. The scaling process can be clarified by the film and nuclei formation mechanism. The room temperature model test with tracer technique indicated that the scaling formation can be explained by the high concentration of TiCL? around the reactor wall and its long residence time. According to our results and others works, a new method for avoiding scaling and clogging of the reactors has been brought forward. |
| 语种 | 中文 |
| 公开日期 | 2013-09-16 |
| 页码 | 75 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1386]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 王志. 四氯化钛高温气相氧化法制备钛白粉的基础研究[D]. 中国科学院过程工程研究所. 中国科学院过程工程研究所. 2004. |
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