【摘要】：我國是稀土資源大國,Ce元素豐度最高,作為稀土元素中的一員,具有獨(dú)特的4f電子結(jié)構(gòu),其氧化物己被廣泛用于紫外吸收劑、發(fā)光材料、汽車尾氣凈化催化劑、拋光劑、玻璃的化學(xué)脫色劑、耐輻射玻璃、電子陶瓷等。納米氧化鈰由于粒徑比較小,具有高的表面效應(yīng)、量子尺寸效應(yīng)、小尺寸效應(yīng)以及宏觀量子隧道效應(yīng)等特性,因此產(chǎn)生了與傳統(tǒng)材料不同的許多特殊性質(zhì),成為近年來材料科學(xué)中研究的熱點(diǎn)。而納米氧化鈰材料的粒徑分布、形貌等均對其性能有影響,因此可控合成納米氧化鈰成為研究的課題。本文的主要目的是水熱法可控合成納米氧化鈰,并對其形貌、結(jié)構(gòu)和催化性能進(jìn)行表征。研究課題的主要內(nèi)容和結(jié)果如下：1.無模板核殼結(jié)構(gòu)氧化鈰的水熱合成采用水熱法,在無模板的條件下120℃反應(yīng)24小時(shí)合成核殼結(jié)構(gòu)氧化鈰。以六水合硝酸鈰為鈰源,尿素為沉淀劑,檸檬酸為形貌控制劑,雙氧水為氧化劑,正丁醇為輔助溶劑,制備得到核殼結(jié)構(gòu)納米氧化鈰。我們通過低倍透鏡、高倍透鏡等測試手段對所得產(chǎn)物及中間態(tài)等進(jìn)行表征,根據(jù)中間產(chǎn)物明顯的變化過程,探討其生長機(jī)理為成核-聚集、奧氏熟化過程,CO催化測試結(jié)果表明核殼結(jié)構(gòu)氧化鈰具有良好的催化活性。2.花狀納米氧化鈰的水熱合成以七水合氯化鈰為鈰源,N,N-二甲基甲酰胺為沉淀劑,氯酸鉀為氧化劑水熱合成花狀結(jié)構(gòu)氧化鈰。在無模板輔助下,180℃水熱4小時(shí)合成尺寸范圍為200-500納米的花狀結(jié)構(gòu)納米氧化鈰顆粒。我們通過低倍透鏡、X射線衍射等測試手段對所得產(chǎn)物及中間態(tài)等進(jìn)行表征,發(fā)現(xiàn)中間過程中物相由兩相最終變?yōu)橐幌?對其生長機(jī)理進(jìn)行探討,主要包括成核-自組裝-氧化過程。CO催化測試結(jié)果表明花狀結(jié)構(gòu)氧化鈰具有良好的催化活性。3.以(220)為主要暴露晶面的氧化鈰納米顆粒的水熱合成以六水合硝酸鈰為鈰源,烏洛托品為沉淀劑,聚乙烯吡咯烷酮為表面活性劑,180℃水熱100分鐘合成13-17納米之間的邊緣明顯的顆粒。我們通過低倍透鏡、高倍透鏡等測試手段對所得產(chǎn)物及改變不同條件等進(jìn)行表征,探討其影響因素,確定最佳反應(yīng)時(shí)間、烏洛托品以及聚乙烯吡咯烷酮添加量。CO催化測試結(jié)果表明13-17納米之間的氧化鈰顆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，

本文編號：2272123