【作者】 孙剑；

【导师】 刘守新；

【作者基本信息】 东北林业大学 ， 林产化学加工工程， 2010， 硕士

【摘要】 随着经济的发展和社会的进步,由挥发性有机物VOCs (Volatile organic compounds)造成的室内空气污染已引起人们广泛关注。大部分室内挥发性有机物都是有毒的,环境保护组织已经证实室内空气质量的好坏是影响人类健康的重要因素之一。这些VOCs包括甲醛、苯、甲苯、低级醇、酮、含氯有机物等,主要来源于油漆,涂料,溶剂,防腐剂,空气清新剂和消毒剂。其中20余种能直接对人造成伤害甚至致癌,如甲醛、苯及苯系物和有机过氧化物等。目前,TiO2多相光催化在环境保护领域内的水和气相有机、无机污染物的光催化去除方面取得了较大进展,被认为是一种极具前途的环境污染深度净化技术。同时活性炭等吸附材料的吸附净化技术被普遍应用,但是由于各自的优缺点,将两者结合起来将是室内空气净化中最具前景的技术之一。而近些年人们越来越重视贵金属的热催化作用,贵金属在低温热催化氧化CO和VOCs等污染物方面具有很大潜力,而将吸附、光催化和贵金属的热催化结合,无疑在净化室内VOCs方面具有很大的新意。本文采用溶胶-凝胶法合成了稀土La掺杂TiO2催化剂,在自行设计的一套反应装置中,以甲苯为模拟污染物,系统的研究了掺杂量、热处理温度等参数对催化剂去除甲苯性能的影响,并在此基础上引入贵金属,考察了贵金属的掺杂量及反应温度等因素对催化剂降解甲苯的影响,而后将复合催化剂负载在ACF上,制备出Pt/LaTiO2/ACF复合催化剂,并考察了吸附、光催化和热催化的协同作用。并结合SEM、XRD和XPS等表征手段分析复合材料表面相貌和晶相结构。以GC-MS联用技术检测复合材料对甲苯去处中间产物的种类和分布。实验结果如下：1.以钛酸四丁酯和硝酸镧为原料,采用溶胶凝胶法,制备出稀土La掺杂TiO2光催化剂薄膜。研究表明：La掺杂可提高催化剂的可见光催化活性,2.8%La/TiO2-500℃在60min内即可完全去除6110.18mg·m-3的气相甲苯；掺入的La以La2O3的形式分布在TiO2表面,并形成Ti-O-La键；La掺杂可抑制TiO2锐钛矿相向金红石相转变、提高相转变温度、减小晶粒尺寸及增大催化剂比表面积；La/TiO2薄膜表面光滑、致密,La的引入能有效抑制TiO2膜气孔的产生；La掺杂可提高TiO2在可见光区的吸收,使催化剂吸收边向长波移动；La的f轨道的电子跃迁是催化剂可见光活性提高的重要原因。2.沉积在催化剂表面的Pt以吸附氧和单质的形式存在,以吸附氧形式为主。而通过光沉积Pt制备的Pt-La2O3/TiO2复合催化剂,催化剂表面羟基官能团OH-伸缩振动明显增强。Pt的掺入没有引起TiO2相结构的变化,Pt的掺入减小了晶粒尺寸并增大了催化剂的比表面积。圆形纳米Pt均匀地分布在La2O3/TiO2上,没有发生团聚现象,尺寸分布比较均一,大约为5nm-10nm。Pt的沉积增加了催化剂对可见光的吸收。通过光沉积Pt所制备的Pt-La2O3/TiO2催化剂比TiO2和La2O3/TiO2具有更高的可见光催化活性。3.在不同体系(LaTiO2, Pt/LaTiO2, Pt/LaTiO2/ACF)对初始浓度为13872.3 mg／m3的甲苯的降解发现,ACF的负载使Pt/LaTiO2/ACF相对于其它两种催化剂对于甲苯的吸附提高很大,Pt/LaTiO2/ACF可以在60min内完全降解初始浓度为13872.3 mg／m3的甲苯。吸附,光催化和热催化之间的有机结合大大增强了该负载型催化剂对甲苯的降解能力。TiO2/ACF和Pt/La0.28Ti10O2/ACF降解甲苯过程中产生的中间产物在种类和含量上具有较大差异。TiO2/ACF的中间产物共有9种,.中间产物以醇类、醚类、苯酚类、酸类、酮类等为主,同时含有少量的长链烷烃,中间产物种类比较宽泛,含量较大。Pt/La0.28Ti10O2/ACF的中间产物共有8种,全部为长链烷烃,可见甲苯在催化剂的作用下,甲苯中所含有的苯环被彻底打开,表明Pt/La0.28Ti10O2/ACF相对于TiO2/ACF的催化活性有很大很高。更多还原

【Abstract】 With the developing of economics and society, indoor air pollution caused by VOCs (Volatile organic compounds) has caused widespread concern. Most indoor volatile organic compounds are toxic. Worldwide environment organizationss have confirmed that indoor air quality is an important factor that affecting human health., which includes formaldehyde, benzene, toluene, alcohols, ketones, chlorinated organics, mainly from paint, solvents, preservatives, deodorants and disinfectants. More than 20 species can damage or cause directly on human cancer, such as formaldehyde, benzene and benzene and other organic peroxides.At present, TiO2 Photocatalysis have made great progress in the field of water and gas phase and was considered as a promising environmental purification technology. At the same time absorbent material is widely applied, such as activated carbon. Considering both the advantages and shortcomings of photocatlysis and adsorption, combining them together for a high efficient composites will be a promising technologies. in recent years, the thermal catalytic of noble metal has been caused widely concern, which can destroy VOCs at low temperature and is very potential, combining adsorption, photocatalytic and thermal catalytic is great new idea for controlling indoor air quality.In this paper, rare earth La doped TiO2 catalyst were synthesized by sol-gel, toluene oxidation was reacted in self-designed device, studying the influence of noble metals doped and reaction temperature on the toluene photocatalytic degradation. Composite materials were characterized by SEM, XRD and XPS.GC-MS was used to analyze composite materials on the toluene place types and distribution of intermediate products. The following are the results:1. La doped TiO2 photocatalyst were prepared by sol-gel method. The activity of the photocatalyst was investigated through degradation of Toluene under artificial visible light. X-ray Photoelectron Spectroscopy(XPS), Uv-vis Diffuse Reflectance Spectra(DRS), X-ray Diffraction analysis(XRD), Scanning Electron Microscope(SEM) and N2 adsorption isotherm were used for catalyst characterization. The results showed that La doped TiO2 exhibited significant improvement of visible light activity. La doping could improve dispersion of TiO2, inhibit particle size agglomeration and retard phase transformation. Doped La can extend the light response of TiO2 to visible light region. Inaddition, narrower band gap formed by La-doping was beneficial to the high visible light photocatalytic activity.2. Pt deposited on the catalyst surface existed in the style of adsorbed oxygen and simple substance. As Pt deposition through light Pt-La2O3/TiO2 prepared composite catalyst, hydroxyl groups OH-stretching on the catalyst surface vibration significantly increased. Pt incorporation did not change phase structure of TiO2, Pt incorporation decreases grain size and increase the catalyst surface area. Pt uniformly distributed on the surface of nano-Pt La2O3/TiO2 and agglomeration did not happened, size distribution of catalyst were uniform, about 5nm-10nm. Pt can make catalyst absorb more visible light. Pt-La2O3/TiO2 performed much higher visible light photocatalytic activity than La2O3/TiO2 and TiO2.3. Through the results of toluene degradation In the different systems (LaTiO2, Pt/LaTiO2, Pt/LaTiO2/VACF), We can find ACF loading can make Pt/LaTiO2/ACF adsorbed much toluene compared to the others, Pt/LaTiO2/ACF can degraded the initial concentration of 13872.3 mg/m3 of toluene within 60min. Combining adsorption, photocatalytic and thermal catalytic can greatly enhance the catalyst activity. Degradation intermediates contents and species were different in the degradation process by TiO2/ACF and Pt/La0.28TiO2/ACF. As TiO2/ACF, nine species intermediates products existed, concluding alcohols, ethers, phenols, acids, ketones, etc, the same small amount of long-chain alkanes, intermediate species in broad, high content. Pt/La0.28Ti02/ACF has eitht intermediate products, all of them were long-chain alkanes, we can find that benzene ring can be opened completely in the toluene degradation process, Pt/La0.28TiO2/ACF performed higher catalytic activity compared to TiO2/ACF.更多还原