【作者】 吴艳香；

【导师】 蒋新；

【作者基本信息】 浙江大学 ， 化学工程， 2007， 硕士

【摘要】 光催化技术是当今科学研究的重点，而纳米技术的高速发展为纳米光催化技术的应用提供了极好的机遇。目前研究最多的光催化剂是纳米TiO₂，由于它具有高比表面积和表面能，活性点多，催化活性和选择性大大高于传统催化剂，在环保、能源材料、化工等领域有着广阔的应用前景。但是纳米TiO₂极易团聚，导致催化活性下降甚至失活，因此高催化活性TiO₂催化剂的研发是影响其实用化的关键。本文利用新型制备技术一吸附相反应技术在SiO₂载体表面制备出小粒径高分散性的TiO₂／SiO₂纳米复合材料，并研究了其光催化性能。首先综述了纳米TiO₂的晶体结构、特性和应用，详细阐述了纳米复合材料制备方法的优缺点和吸附相反应技术的研究进展以及TiO₂光催化机理和影响光催化活性的各种因素，并对气固光催化反应动力学作了简单介绍。利用透射电镜（TEM），电子色散能谱仪（EDAX），X射线衍射仪（XRD），比表面积测定仪（BET）等检测手段对纳米TiO₂／SiO₂结构进行表征，以甲苯气体为模拟反应物探讨影响光催化活性的因素，光催化降解过程符合一级动力学方程，由FT-IR和气-质联用检测推断甲苯光催化降解的中间产物。运用一级动力学方程拟合反应速率常数，比较了不同制备条件和热处理条件下催化剂的光催化活性大小，分析光催化影响因素，并与传统浸渍法和商品P25进行对比，结果表明：（1）制备温度的变化对制备的催化剂活性改变不是很大；水量增大或者钛酸丁酯浓度的增加，光催化活性都会提高，降解速率的快慢与Ti含量和钛酸丁酯的加入量存在近似线性的关系。（2）焙烧温度升高和时间增长，TiO₂结晶趋于完善，光催化降解速率增大，焙烧温度达到900℃时，晶粒粒径变大，表面积下降，催化活性随之下降，但晶型并没有发生改变，仍保持纯锐钛矿型，晶粒粒径仍在10nm以下。（3）吸附法制备的TiO₂／SiO₂反应速率常数是浸渍法的2倍，与商品P25进行对比，催化活性要高于P25，晶粒粒径是影响光催化活性高低的主要因素。更多还原

【Abstract】 Nanometer technology develop in rapid speed, then provided good opportunity for the technical application of the nanometer photocatalysis, so the photocatalysis technique becomes the hostpot in science research nowadays. At present, nanometer TiO₂ photocatalyst with large specific sueface atea, high surface energy and many activity sites is studied mostly and has wide application in enviroment protection, energy materials and chemical industry and so on, because its catalytic activity and selectivity are higher than tradional catalyst greatly. But the catalytic activity of nanometer TiO₂ is easy to decline even lost by reason of its aggregation effect. Therefore, the research of TiO₂ with high photoactivity is the key for its industrialization.In this dissertation, photocatalytic property of TiO_/SiO₂ nanocomposite materials synthesized by new method-adsorption phase reaction technique was studied. TiO₂ with small grain size is dispersed on the suefaceof SiO₂.First, crystal struction,characteristic and application of nano-TiO₂ were reviewed.The author introduced maily advantages and disadvantages of the preparation methods of nanocomposite materials, research status of adsorption phase reaction technique, photoatalytic mechanics of TiO₂ and various photocatalytic factors. Photocatalytic reaction dynamics of gas-solid were also generalized.Nano-TiO₂/SiO₂ was characterized by means of TEM, EDAX, XRD and BET. The factors affecting photocatalytic activity were discussed in process of the degradation of gaseous toluene, which was agreement with first-order dynamics equation. The intermediate products were detected and infered by Fourier-trasform infrared spectroscopy （FT-IR）and gas chromatography-mass （GC-MS）on-line. The activity of catalysts with conditions of preparation and heat treatment is compared using first-order reaction rate constants and the influencing factors were analysed. The activity of self-synthesis was compared with traditional impregnation method and P25 commodity. The results showed:（1） Catalytic activity was affected by preparation temperature least; the photocatalytic activity improved with increasing the amount of water and tetrabutyl titanate.Tha rate of degradation was linear with Ti content and the amount of tetrabutyl titanate.（2） Calcined temperature and time could improve crystallnity and acceleratedphotocatalytic degradation. When Calcined temperature reached 900℃, the photocatalytic activity declined because the grain size became large and specific surface area declined. But the TiO₂ still keep anatase without crystal transformation.（3） The observed rate constants of TiO₂/SiO₂ prepared by adsorption phase reaction technique was half past one than impregnation method preparation and the photocatalytic activity is higher than P25, because the grain size was major facror influnced photocatalytic activity.更多还原