水热法合成纳米氧化铈及其CO催化性能的研究
发布时间：2018-10-15 09:36
【摘要】：我国是稀土资源大国,Ce元素丰度最高,作为稀土元素中的一员,具有独特的4f电子结构,其氧化物己被广泛用于紫外吸收剂、发光材料、汽车尾气净化催化剂、抛光剂、玻璃的化学脱色剂、耐辐射玻璃、电子陶瓷等。纳米氧化铈由于粒径比较小,具有高的表面效应、量子尺寸效应、小尺寸效应以及宏观量子隧道效应等特性,因此产生了与传统材料不同的许多特殊性质,成为近年来材料科学中研究的热点。而纳米氧化铈材料的粒径分布、形貌等均对其性能有影响,因此可控合成纳米氧化铈成为研究的课题。本文的主要目的是水热法可控合成纳米氧化铈,并对其形貌、结构和催化性能进行表征。研究课题的主要内容和结果如下：1.无模板核壳结构氧化铈的水热合成采用水热法,在无模板的条件下120℃反应24小时合成核壳结构氧化铈。以六水合硝酸铈为铈源,尿素为沉淀剂,柠檬酸为形貌控制剂,双氧水为氧化剂,正丁醇为辅助溶剂,制备得到核壳结构纳米氧化铈。我们通过低倍透镜、高倍透镜等测试手段对所得产物及中间态等进行表征,根据中间产物明显的变化过程,探讨其生长机理为成核-聚集、奥氏熟化过程,CO催化测试结果表明核壳结构氧化铈具有良好的催化活性。2.花状纳米氧化铈的水热合成以七水合氯化铈为铈源,N,N-二甲基甲酰胺为沉淀剂,氯酸钾为氧化剂水热合成花状结构氧化铈。在无模板辅助下,180℃水热4小时合成尺寸范围为200-500纳米的花状结构纳米氧化铈颗粒。我们通过低倍透镜、X射线衍射等测试手段对所得产物及中间态等进行表征,发现中间过程中物相由两相最终变为一相,对其生长机理进行探讨,主要包括成核-自组装-氧化过程。CO催化测试结果表明花状结构氧化铈具有良好的催化活性。3.以(220)为主要暴露晶面的氧化铈纳米颗粒的水热合成以六水合硝酸铈为铈源,乌洛托品为沉淀剂,聚乙烯吡咯烷酮为表面活性剂,180℃水热100分钟合成13-17纳米之间的边缘明显的颗粒。我们通过低倍透镜、高倍透镜等测试手段对所得产物及改变不同条件等进行表征,探讨其影响因素,确定最佳反应时间、乌洛托品以及聚乙烯吡咯烷酮添加量。CO催化测试结果表明13-17纳米之间的氧化铈颗粒具有良好的催化活性。
[Abstract]:China is a large country of rare earth resources, Ce element abundance is the highest, as a member of rare earth elements, with a unique 4f electronic structure, its oxides have been widely used in ultraviolet absorbent, luminescent materials, automobile exhaust purification catalyst, polishing agent. Glass chemical decolorizing agent, radiation resistant glass, electronic ceramics and so on. Due to its small particle size, high surface effect, quantum size effect, small size effect and macroscopic quantum tunneling effect, nano-cerium oxide has many special properties different from traditional materials. In recent years, it has become a hot spot in material science. The particle size distribution and morphology of nano-cerium oxide materials have influence on their properties, so the controllable synthesis of nano-cerium oxide has become a research topic. The main purpose of this paper is to synthesize cerium oxide nanocrystalline by hydrothermal method, and to characterize its morphology, structure and catalytic performance. The main contents and results of the research are as follows: 1. The hydrothermal synthesis of core-shell cerium oxide without template was carried out by hydrothermal method, and the core-shell structure cerium oxide was synthesized at 120 鈩，
本文编号：2272123
[Abstract]:China is a large country of rare earth resources, Ce element abundance is the highest, as a member of rare earth elements, with a unique 4f electronic structure, its oxides have been widely used in ultraviolet absorbent, luminescent materials, automobile exhaust purification catalyst, polishing agent. Glass chemical decolorizing agent, radiation resistant glass, electronic ceramics and so on. Due to its small particle size, high surface effect, quantum size effect, small size effect and macroscopic quantum tunneling effect, nano-cerium oxide has many special properties different from traditional materials. In recent years, it has become a hot spot in material science. The particle size distribution and morphology of nano-cerium oxide materials have influence on their properties, so the controllable synthesis of nano-cerium oxide has become a research topic. The main purpose of this paper is to synthesize cerium oxide nanocrystalline by hydrothermal method, and to characterize its morphology, structure and catalytic performance. The main contents and results of the research are as follows: 1. The hydrothermal synthesis of core-shell cerium oxide without template was carried out by hydrothermal method, and the core-shell structure cerium oxide was synthesized at 120 鈩，
本文编号：2272123
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