火焰化学气相沉积法制备多晶纳米二氧化钛及其在气体净化中的应用

Mixed Crystal Structures of Nano TiO_2 by Flame Chemical Vapor Deposition Process and Applications in Photocatalytic Gas Purifications

综述了作者近年来在火焰化学气相沉积(CVD)法制备多晶纳米二氧化钛及其在光催化气体净化中应用的研究成果。总结了以工业丙烷为燃料、空气为催化剂、四氯化钛为先驱物的火焰CVD法制备多晶纳米二氧化钛中热负荷对燃烧室内的温度分布和金红石含量的影响。以光致发光(PL)光谱为表征手段,研究了金红石含量对光激电子和空穴的分离作用。用管式光催化反应系统,研究了初始浓度和相对湿度对多晶纳米二氧化钛光催化降解挥发性有机物(VOC)气体和氨气的影响,及最佳光催化效率的金红石含量。针对多晶纳米二氧化钛在低相对湿度下光催化降解效率低的缺陷,用复合法对其性能进行了改进,研究了改进的光催化剂在低相对湿度和干燥空气中光催化降解苯的效率。对500 m3/h模块化的填料式光催化气体净化设备进行了净化效率和催化剂寿命实验,讨论了光催化饱和浓度对净化设备设计的影响。

Progress achieved by the authors in recent years on synthesis of mixed crystal structures of Tit2 nanoparticles by flame chemical vapor deposition （CVD） process of the oxidation of titanium tetrachloride （TIC14） in industry propane/air turbulent flame and on applications in photocatalytic purification of gas pollutants have been summarized. Effects of reactor heat flux on temperature profiles and rutile fraction of mixed crystal structures of Tit2 nanoparticles, and effects of rutile fraction on the separation of electron- hole pairs based on PL intensities have been summarized. Photodegradation of volatile organic compounds and ammonia are studied by using a tubular photoreactor. Effects of initial concentration and relative humidity on degradation efficiency have been investigated experimentally and optimum rutile fraction for photodegradation efficiency has been examined. Nano Tit2 has been successfully modified to achieve high photodegradation efficiency at low relative humidity or even in dry air. Tests on purification efficiency and lifetime of a 500 ma/h modular filer photocatalytic gas purifier have been performed, and effects of photocatalytic saturation behavior on design of gas purifier have been discussed.