【作者】 张茂林；

【导师】 傅家谟； 盛国英；

【作者基本信息】 中国科学院研究生院（广州地球化学研究所） ， 环境科学， 2004， 博士

【摘要】 在环境污染日益严重的今天，净化和修复环境已经成为当务之急。在各种环境净化方法中，半导体异相光催化降解技术作为一种新型的环境净化技术已经越来越为人们所重视。但要使半导体异相光催化降解技术在环境治理中得以推广使用，在提高光催化效率、制备新型高效的光催化剂、催化剂的回收和再生以及开发合理实用的光催化反应器等方面还有待于进一步研究探索。通过查阅大量文献资料，在前人工作的基础上，本论文就以上几个方面的问题进行了初步研究。同时，在光催化剂制备的基础上，对两类常见的气体污染物（卤代烃和羰基化合物）进行了异相光催化降解研究，并取得了一些有益的成果，为异相光催化技术进一步实用化提供了理论依据。 首先，通过负载技术，将共沉淀法制得的ZnO-SnO₂纳米复合光催化剂负载在泡沫镍上制成了ZnO-SnO₂／泡沫镍负载型纳米光催化剂，以三氯乙烯为模型反应物，研究了反应气流速、湿度等因素对反应的影响，同时考察了催化剂的失活特征，并用扫描电子显微镜技术对负载型纳米光催化剂反应前后的表面状态进行了分析。结果表明，ZnO-SnO₂／泡沫镍负载型纳米光催化剂在各种湿度范围内都具有较高的催化活性，能有效地将三氯乙烯光催化降解消除。同时，该负载型纳米光催化剂具有较强的抗失活能力。 其次，以ZnSO₄·7H₂O和SnCl₄·5H₂O为原料，利用NH₂·H₂O做沉淀剂，采用共沉淀法，制备了ZnO-SnO₂复合氧化物光催化剂。用现代技术手段如TEM、XRD、UV-Vis等对ZnO-SnO₂光催化剂的微观结构和性质进行了表征。以甲基橙降解为模型反应，考察了催化剂的光催化活性，并对结构和性能之间的关系进行了讨论。结果表明，复合氧化物光催化剂主要由纳米级ZnO和SnO₂组成，并且对甲基橙的降解反应呈现出较高的光催化活性，并且350℃煅烧样品的光催化活性与P25 TiO₂相当。但是随着煅烧温度的升高，复合氧化物光催化剂的光催化活性大大降低，当煅烧温度大于700℃时，还有少量较弱光催化活性的纳米Zn₂SnO₄生成。 最后，以钛酸丁酯为原料以及醋酸为酸催化剂，通过溶胶-凝胶的技术和浸渍方法，在醋酸水溶液中制备出了复合负载型光催化剂TiO₂／SiO₂。用TEM、XRD、BET等技术手段对TiO₂／SiO₂进行了表征。在循环式流动床光催化反应系统中对典型室内污染水平的四种羰基化合物混合物进行了光催化降解实验，研究了气体流速、湿度、氧气浓度、光照时间等因素对光催化反应的影响。结果表明，复合负载型光催化剂TiO₂／SiO₂具有较好的吸附性能和较高的光催化活性。在流动床反应器中，四种羰基化合物都能被有效地光中国科学院广州地球化学研究所博士学位论文催化降解消除。并且四种化合物降解活性为:丙醛>丙酮>乙醛>甲醛。复合负载型光催化剂TIOZ/5102有望发展成为一种良好的空气净化材料。 研究工作的特色和创新之处:（1）利用氨水做沉淀剂制备纳米复合氧化物ZnO一Sn仇光催化剂过程中，沉淀不需要洗涤处理，这样不但省时、简化操作，而且合成温度较低，减少能耗。同时，实验还发现，氨或钱离子在前驱物中存在对光催化剂的合成是有利的，在相同实验条件下，利用氨水做沉淀剂制备出的Zno一Sno:复合氧化物的粒径比前人实验中利用NaOH做沉淀剂制备出的复合氧化物要小，并且光催化活性更高。（2）纳米ZnO一Sn仇/泡沫镍负载型光催化剂有强的抗失活能力，在无水状态下，光照ZO5h后，催化剂光催化活性稳定，没有出现失活现象。（3）以醋酸作为酸催化剂，利用简单的溶胶一凝胶技术，在醋酸水溶液中制备出了复合负载型光催化剂TIOZ/5102。制得的光催化剂比表面积很大，并且负载的TIOZ粒径很小，平均粒径只有IOnm左右。与常用的HCI和HNO。等无机酸作催化剂相比，在本研究中，水解反应时钦酸丁酷水解缓慢，容易控制，同时负载操作简单方便，也不需要洗涤过程，制得的Ti02粒径更小，比表面积更大。（4）在循环式流动床光催化反应系统中同时对四种碳基化合物进行了光催化降解实验，并且发现四种化合物降解活性为:丙醛>丙酮>乙醛>甲醛，这与四种化合物在催化剂表面吸附能力的大小相一致，从而再一次证明了异相光催化反应是一个表面反应。更多还原

【Abstract】 Currently, the issue of environmental pollution is more and more serious, so environmental cleaning and environmental remediation is an urgent task. Among various techniques for purifying environment, the photocatalytic degradation technology is paid greater attention as a new environment-purifying technique. However, we will continue research and development on improving the photocatalytic efficiency, recovering and reusing the photocatalyst, designing and fabricating reasonable and applied photocatalytic reactor and otherwise, in order that the heterogeneous photocatalysis is widely used for the practical water and air purification. In this dissertation, above-mentioned issues were studied on the base of previous researches. At the same time, the photocatalytic degradation of two kind common air pollutants (chlorinated hydrocarbon and carbonyl compound) was investigated. Some valuable results were obtained, and they will be significative for the practical application of the gas-solid heterogeneous photocatalysis.Firstly, a coupled oxide ZnO-SnO2, which was prepared using the co-precipitation method, was immobilized to porous nickel mesh by coating, and a coupled oxide ZnO-SnO2 supported photocatalyst was prepared. The photocatalytic degradation performance of the supported photocatalyst on gaseous model chemical trichloroethylene (TCE) was investigated in a flow through photocatalytic reactor. Some factor such as the gas flow rate, the relative humidity etc., which influence the photocatalytic conversion efficiencies of TCE, were studied, and the lifetime of the supported photocatalyst also was tested. At the same time, the surface character of the supported photocatalyst during the test was observed by the scanning electron microscope (SEM). It is found that the gaseous photocatalysis over the supported photocatalyst is an efficient method for chlorinated hydrocarbon abatement, and ca.100% conversion was found for TCE with a concentration examined up to 400 ppmv in flow-through dry synthetic gas stream. Moreover, the experiments of repeated run indicated the supported photocatalyst displayed long lifetime, and the deactivation of the supported photocatalyst had not been observed within the 205 h tested period in the present experiment, although the surface of photocatalyst changed greatly during the use of the photocatalyst.Secondly, a coupled oxide ZnO-SnO2 was prepared using the co-precipitation method, ZnSO4-7H2O and SnCl4-5H2O were used as the starting materials and NH3 ?H2O as the precipitant. The coupled oxide was characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and UV diffuse reflectance spectrum (DRS). The photocatalytic activity of the coupled oxide was studied using methyl orange as a mode organic pollutant. The relationship between the photocatalytic activity and the microstructure of nanometer coupled oxides was also discussed in the dissertation. Experimental results showed that the coupled oxide mainly consist of nanometer ZnO and SnO2, and they have the same excellent photocatalytic activity as Degussa P25 Ti02 for the degradation of methyl orange (MO). But the photocatalytic activity of the coupled oxides decreases rapidly with the increase of the calcination temperature, and a small amounts of nanometer Zn2SnO4 was formed in the mixture of coupled oxides when the calcination temperature is higher than 700 ℃.Finally, a nano-sized titania (anatase) was immobilized to silica gel in the acetic acid solution by the sol-gel technique and the repeated dip coating method using the tetra-n-butylDoctoral Dissertation, Gangzhou Institute of Geochemistry, Chinese Academy of Sciencestitanate as main raw material and acetic acid as the acid catalyst to prepare a coupled photocatalyst TiC>2/SiO2. Meanwhile the structure and properties of the coupled photocatalyst were studied by means of many modern analysis techniques such as TEM, XRD, BET. The photocatalytic degradation of four carbonyl compounds mixture was carried out by using a coaxial triple-cylinder-type更多还原