纳米二氧化钛的气相合成

Synthesis of nanosized titanium dioxide in gas phase

综述了TiCl4氢氧焰水解法、TiCl4气相氧化法、钛醇盐气相氧化法、钛醇盐气相水解法和钛醇盐气相热解法合成纳米二氧化钛的技术进展。气相法合成纳米二氧化钛的研究热点是工艺参数、反应物的混合方式、添加剂、外加电场和反应器型式对纳米二氧化钛的微结构和性能的影响,用计算流体力学、反应动力学与气相颗粒形成模型相结合来模拟过程和改进反应器设计也是一个令人关注的研究领域。TiCl4气相氧化法由于其具有经济、环保和生产工艺的柔性等优点而最具竞争力。控制纳米二氧化钛粒子的形态、粒径分布、比表面积和晶型组成以及防止反应器壁二氧化钛结疤是气相法规模化生产纳米二氧化钛需重点解决的问题。

The gas phase methods include the flame hydrolysis of TiCl4, the vapor phase oxidation of TiCl4, the vapor phase oxidation of Ti(OR)4, the vapor phase hydrolysis of Ti(OR)4 and the vapor phase pyrolysis of Ti(OR)4 . The synthesis of nano-sized titanium dioxide in gas phase is reviewed. The advantages and disadvantages of these methods are evaluated. The research progress and developing trend of synthesis of nanosized titanium dioxide in gas phase is discussed. The focus of research is on the effect of process parameters, the method of reactant mixing, additives, external electric field and reactor configuration on the microstructure and property of nanosized titanium dioxide. Computational fluid dynamics and reaction kinetics in combination with gas phase particle models are applied in the process simulation and improvement of reactor designs, which are also an attractive research field. The vapor phase oxidation of TiCl4 is the most competitive because of its economy, environmental protection and flexible process technology. The key problems in the process of producing nanosized titanium dioxide on a large scale in gas phase methods are in the aspects of controlling the morphology, particle size distribution, specific surface area and phase composition of nanosized titanium dioxide and preventing formation of wall scale in the reactor.