本文選題：二氧化鈰　切入點(diǎn)：空心結(jié)構(gòu)　出處：《濟(jì)南大學(xué)》2017年碩士論文

【摘要】：納米二氧化鈰(CeO_2)作為一種性質(zhì)獨(dú)特的稀土氧化物,具有優(yōu)異的催化活性、良好的熱穩(wěn)定性和化學(xué)穩(wěn)定性以及強(qiáng)的氧儲(chǔ)存/釋放能力,常被用作貴金屬納米粒子的載體以增強(qiáng)催化劑性能。貴金屬-CeO_2復(fù)合催化劑廣泛應(yīng)用于CO催化氧化、水煤氣轉(zhuǎn)換、NOx還原以及固態(tài)氧化物燃料電池等領(lǐng)域,對(duì)治理環(huán)境污染和解決能源危機(jī)有重大意義。CeO_2與貴金屬之間存在復(fù)雜的協(xié)同催化效應(yīng),而貴金屬-CeO_2的結(jié)構(gòu)類(lèi)型與二者之間的協(xié)同效應(yīng)有著密切的關(guān)系。因此,設(shè)計(jì)不同結(jié)構(gòu)的貴金屬-CeO_2可以調(diào)控催化劑的催化活性。本論文從貴金屬-CeO_2催化劑結(jié)構(gòu)類(lèi)型出發(fā),利用界面反應(yīng)進(jìn)行控制合成,并分別從材料制備、結(jié)構(gòu)表征、形成機(jī)理以及催化性能測(cè)試等幾個(gè)方面進(jìn)行了系統(tǒng)的研究。1.界面反應(yīng)直接合成高催化活性和熱穩(wěn)定性的鑲嵌型CeO_2-Pt納米管在沒(méi)有任何表面活性劑參與且不涉及任何表面修飾,通過(guò)界面反應(yīng)合成了一種基于CeO_2納米管鑲嵌超小Pt納米顆粒的催化劑。具體地說(shuō),當(dāng)Ce(OH)CO3納米棒和H2PtCl6引入到NaOH溶液中時(shí),Ce(OH)CO3和NaOH之間發(fā)生固-液界面反應(yīng)。形成的Ce(OH)3沉積在Ce(OH)CO3納米棒的外表面。在界面反應(yīng)中緩慢形成的Ce(OH)3由于帶有正電荷,將靜電吸引帶有負(fù)電荷的Pt物種,形成Pt物種和Ce(OH)3的均勻混合物。當(dāng)除去剩余的Ce(OH)CO3并H2還原后,得到CeO_2納米管鑲嵌Pt納米顆粒的空心復(fù)合材料。由于催化活性組分Pt納米顆粒的超小尺寸和Pt與CeO_2之間的緊密結(jié)合,即使在溫度高達(dá)700℃,該催化劑依然展現(xiàn)了高的CO氧化催化活性和優(yōu)良的熱穩(wěn)定性,這表明鑲嵌型CeO_2-Pt納米管具有高溫催化反應(yīng)的應(yīng)用前景。2.結(jié)合雙模板界面反應(yīng)合成非對(duì)稱(chēng)空心CeO_2-Au納米結(jié)構(gòu)具有復(fù)雜空心結(jié)構(gòu)的材料由于其獨(dú)特結(jié)構(gòu)特征,賦予材料額外的性能。到目前為止,這種結(jié)構(gòu)主要通過(guò)硬模板或犧牲模板法來(lái)實(shí)現(xiàn),獲得的空心結(jié)構(gòu)一般為空心球包空心球、納米管包納米管等簡(jiǎn)單對(duì)稱(chēng)性結(jié)構(gòu),這在一定程度上限制了復(fù)雜結(jié)構(gòu)空心材料的構(gòu)造。在本文中,我們通過(guò)結(jié)合SiO_2和Ce(OH)CO3雙模板的固-液界面反應(yīng)合成了納米管包空心球的不對(duì)稱(chēng)結(jié)構(gòu)。在實(shí)驗(yàn)中,Ce(OH)CO3納米棒(犧牲模板)鑲嵌SiO_2球(硬模板)復(fù)合材料用NaOH溶液處理,隨后進(jìn)行酸洗滌。與簡(jiǎn)單的空心CeO_2納米管相比,非對(duì)稱(chēng)空心結(jié)構(gòu)CeO_2負(fù)載Au納米顆粒表現(xiàn)出更優(yōu)的CO催化氧化性能。3.界面氧化還原法合成Au@CeO_2-MnO_2納米管夾心式核-殼空心結(jié)構(gòu)由于其高催化活性和穩(wěn)定性受到廣泛關(guān)注。本文中,在沒(méi)有任何表面活性劑參與下,制備了核-殼結(jié)構(gòu)的Au@CeO_2-MnO_2納米管。首先利用Ce(OH)CO3與NaOH溶液發(fā)生固-液界面反應(yīng),在Ce(OH)CO3表面生成一層CeO_2,然后進(jìn)行Au顆粒種子的負(fù)載,再通過(guò)與KMnO4溶液發(fā)生界面氧化還原反應(yīng)進(jìn)行殼層的包覆。KMnO4與Ce(OH)CO3緩慢釋放的Ce3+進(jìn)行反應(yīng),生成CeO_2-MnO_2復(fù)合物。最后經(jīng)過(guò)酸洗除去剩余的Ce(OH)CO3模板,得到Au@CeO_2-MnO_2納米管。由于雙金屬氧化物與夾層內(nèi)Au粒子豐富的接觸面積,Au@CeO_2-MnO_2納米管展現(xiàn)了高的催化CO氧化和4-硝基苯酚還原活性。同時(shí)由于夾層結(jié)構(gòu)的存在,在一定程度上提高了Au納米粒子的穩(wěn)定性。
[Abstract]:Two nano cerium oxide (CeO_2) as a kind of unique properties of rare earth oxides, has excellent catalytic activity, good thermal stability and chemical stability, strong oxygen storage / release capacity, is often used as a carrier of noble metal nanoparticles to enhance the performance of the catalyst. The noble metal -CeO_2 catalyst used in catalytic oxidation of CO. Water gas conversion, NOx reduction and solid oxide fuel cell, the environmental pollution control and solve the energy crisis there is synergistic catalytic effect of complex between.CeO_2 and the significance of precious metals, precious metals and the synergistic effect between -CeO_2 and the two types of structures have a close relationship. Therefore, the design of different structure noble metal -CeO_2 catalyst for catalytic activity can be regulated. In this thesis, the catalyst structure of noble metal -CeO_2 type of control synthesized by interfacial reaction, and separately from the Material preparation, structure characterization, formation mechanism and catalytic properties are also investigated.1. interface reaction system of direct synthesis of high catalytic activity and thermal stability of the inlaid type CeO_2-Pt nanotubes without any surfactant in and do not involve any surface modification, by interfacial reaction to synthesize a catalyst of CeO_2 nanotubes embedded super small Pt nanoparticles based on. Specifically, when Ce (OH) CO3 nanorods and H2PtCl6 into NaOH solution, Ce (OH) of solid-liquid interface reaction between CO3 and NaOH. The formation of Ce (OH) 3 Ce (OH) deposited on the outer surface of the CO3 nanorods formed in slow. The interfacial reaction in Ce (OH) 3 with a positive charge, the electrostatic attraction of negatively charged Pt species, Pt species and Ce (OH) a homogeneous mixture of 3. When removing the residual Ce (OH) CO3 and H2 after reduction, CeO_2 nanotubes embedded Pt nano particles The hollow composite material. Due to the close integration between the catalytic active components of Pt nanoparticles with ultra small size and Pt and CeO_2, even at a high temperature of 700 DEG C, the catalyst still exhibited high catalytic activity for CO oxidation and excellent thermal stability, which indicates that the embedded type CeO_2-Pt nano tube has high catalytic application prospect of.2. the reaction with double template interface synthesis of asymmetric hollow CeO_2-Au nanostructures with complex hollow structure materials because of its unique structure, with additional properties of materials. So far, this structure is mainly realized by hard template or sacrificial template method, hollow ball bag hollow structure obtained generally hollow spheres nanotubes nanotubes package such a simple symmetrical structure, which limits the construction of complex structure of hollow materials to a certain extent. In this paper, we through the combination of SiO_2 and Ce (OH) CO3 double template The solid-liquid interface reaction of asymmetric structure nanotubes hollow spheres. Package in the experiment, Ce (OH) CO3 nanorods (sacrificial template) embedded in SiO_2 ball (hard template) NaOH solution with composite materials, followed by acid washing. Compared with simple CeO_2 hollow nanotubes, asymmetric hollow structure CeO_2 load Au the nano particles exhibit CO catalytic oxidation performance of.3. interface oxidation better reduction synthesis of Au@CeO_2-MnO_2 nanotube sandwich core-shell hollow structure due to its high catalytic activity and stability has attracted extensive attention. In this paper, in the absence of any surfactant in the presence of the core-shell structure of Au@CeO_2-MnO_2 nanotubes were prepared by using Ce (first. OH) CO3 and NaOH solution to the solid-liquid interface reaction in Ce (OH) CO3 surface to form a layer of CeO_2, then the Au seed particles load, then an interfacial redox reaction of shell and KMnO4 solution by The.KMnO4 coated with Ce (OH) CO3 slow release of the Ce3+ reaction, generate CeO_2-MnO_2 composites. Finally after pickling to remove residual Ce (OH) CO3 template, Au@CeO_2-MnO_2 nanotubes. Due to the contact area of double metal oxide and the interlayer of Au particles rich in Au@, CeO_2-MnO_2 nanotubes show high catalytic oxidation of CO and 4- p-nitrophenol reduction activity. At the same time because of the sandwich structure, to a certain extent, improve the stability of Au nanoparticles.

【學(xué)位授予單位】：濟(jì)南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：O643.36;TB333

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本文編號(hào)：1670670