【作者】 李明；

【导师】 邓谦； 彭振山；

【作者基本信息】 湖南科技大学 ， 物理化学， 2010， 硕士

【摘要】 本文介绍了半导体光催化化学研究的发展现状、理论以及现实意义。详细阐述TiO2光催化消除有机污染物机理及其研究现状。制备了(C5H7N2)3AsMo12O40?5H2O/TiO2和RE(RE=La、Ce、Pr、Nd) /TiO2光催化剂。在自行设计和安装的流动连续光催化反应装置中,以甲醇(丙酮)与空气的混合气体模拟室内空气污染物,在可见光或平均波长为253.7nm的紫外灯照射下的进行光催化消除反应,考察了催化剂的光催化活性。运用红外光谱、差热-热重、X-射线衍射、扫描电镜、荧光光谱等表征手段系统研究了催化剂的光谱性质以及结构形态。用溶胶-凝胶法制备了RE(RE=La、Ce、Pr、Nd)/TiO2光催化剂,研究了单一稀土元素的掺杂对TiO2催化活性的影响。通过光催化消除甲醇实验研究了活化温度、不同稀土元素及其掺杂量对催化剂活性的影响。差热-热重、荧光等实验结果表明:由于稀土元素的掺杂,TiO2由锐钛矿向金红石相的转变温度有所提高;光生电子和空穴复合率有所降低,催化性能明显提高。尤其是Pr元素的掺杂对TiO2催化性能的提高最为明显。初始浓度为12.0g?m-3,流速为10.0ml?min-1,催化剂用量为0.1g时,Pr/TiO2催化消除甲醇的消除率达84.0%。对Pr/TiO2催化剂催化消除甲醇反应进行了动力学研究。活化能为20.0kJ?mol-1,表现为一级反应。采用浸渍法制备了(C5H7N2)3AsMo12O40?5H2O/TiO2复合光催化剂,通过一系列表征手段对催化剂进行了研究。由扫描电镜可以看出复合催化剂粒子细化,颗粒分布更为均匀;测定了TiO2以及不同(C5H7N2)3AsMo12O40?5H2O含量的复合催化剂的荧光发射光谱,发现掺杂后催化剂的发射光谱相对强度要明显小于纯的TiO2,说明(C5H7N2)3AsMo12O40?5H2O的掺杂有助于抑制电子-空穴的复合,充分体现了二者的协同效应。(C5H7N2)3AsMo12O40 ? 5H2O掺杂量为5.0wt.%的(C5H7N2)3AsMo12O40?5H2O/TiO2的催化剂活性最好。在甲醇初始浓度为3.2g?m-3、丙酮初始浓度为3.5 g?m-3时,体系流速为10.0ml?min-1时,催化剂的对甲醇和丙酮的消除率达到100.0%。在Au/TiO2紫外光催化消除甲醇研究的基础上,研究了可见光对甲醇的催化消除作用。运用正交试验考察掺杂量、焙烧温度、焙烧时间等制备因素对催化剂可见光催化活性的影响,获得了金含量为1.0wt.%,焙烧温度为200℃时为最佳制备条件。在可见光下,当甲醇气体初始浓度为35.0g?min-1流速为5.0ml?min-1时,催化消除可达62.3%。更多还原

【Abstract】 The thesis introduces the development, theory and practical significance of semiconductor photo-catalysis, and explains TiO2 photo-catalytic elimination mechanism of organic pollutants and its current research condition in detail.The (C5H7N2)3AsMo12O40?5H2O/TiO2 and RE(RE=La、Ce、Pr、Nd)/TiO2 are prepared. The photo-catalytic activity of the photocatalysts is performed in a home-made continuous flow photo-catalytic tube reactor. The photo-catalytic elimination of methanol or acetone is used as model reaction to evaluate the photocatalytic activity of the photo-catalysts under ultraviolet light irradiation or visible light. Spectroscopic properties and structural morphology of catalysts are investigated through means of characterization, such as Infrared Spectrum, DTA-TG, X-ray diffraction, fluorescence spectra, scanning electron microscope, etc.RE(RE= La、Ce、Pr、Nd)/TiO2 photo-catalysts are prepared by sol-gel, The influence of a single rare earth element doping TiO2 on the photo-catalytic activity are researched. The effects of doping content, different types of rare earth elements and activation temperature on the catalytic activity are investigated by photo-catalytic elimination methanol experiment. The TG-DTA and Fluorescence results show that as the doping of rare earth elements, phase transition temperature from TiO2 anatase to rutile are increased and the photo-induced electron and hole recombination rate are decreased,the catalytic performance of rare earth elements doped are significantly improved. The best is Pr/TiO2. When the initial concentration of methanol is 12.0g?m-3and the flow rate is 10.0ml?min-1, the elimination rate of methanol can reach to 84.0% over the 0.1g Pr/TiO2 catalyst. The dynamics law of photocatalytic reaction over the Pr/TiO2 catalyst has been studied. The activation energy of the raection is 20.0KJ/mol, which accords to the first order dynamics law.The composite photo-catalyst (C5H7N2)3AsMo12O40 ? 5H2O/TiO2 are prepared through impregnation and studied through a series of characterization methods. The scanning electron microscope and XRD show that particle size become miniaturized and uniform; The fluorescence emission spectra of TiO2 and composite photo catalyst with different doping content of (C5H7N2)3AsMo12O40?5H2O show that the relative intensity of emission spectrum of (C5H7N2)3AsMo12O40?5H2O/TiO2 is obviously lower than pure TiO2. It indicates that the doping of (C5H7N2)3AsMo12O40?5H2O can help inhibit electron-hole recombination, and fully elaborate the synergistic effect of these two substances. The composite catalyst doped with 5.0wt.% has the highest activity. When the initial concentration of methanol and acetone is 3.2g?m-3 and 3.5 g?m-3 respectively, and the flow is 10.0ml?min-1, the elimination rate of methanol and acetone can reach to 100.0%.On the basis of research on elimination of methanol under UV light, the role of the visible light has been studied. Through orthogonal test, the effection of doping amount, calcination temperature, calcination time on catalytic activities have been investigated. The catalyst doped with 1.0wt.% and activated under 200℃has the highest activity. When the initial concentration of methanol is 35.0g?m-3, and the flow is 5.0ml?min-1, the elimination rate of methanol can reach to 62.3% under visible light.更多还原