【作者】 秦华；

【导师】 李峰；

【作者基本信息】 北京化工大学 ， 化学工程与技术， 2010， 硕士

【摘要】 碳纳米管和碳纳米纤维作为纳米材料和碳材料的结合,具备很多独特的物理化学性质,被广泛应用到复合增强材料、吸附材料、储氢材料、场发射材料、催化剂以及催化剂载体、锂离子电池、传感器、新型混纺材料、肌肉材料以及电子探针等诸多领域,随着研究工作的不断深入,碳纳米管和碳纳米纤维的应用前景将会更加广阔。目前制备碳纳米材料的方法比较常见的仍然是CVD法,近年来CVD法得到较快的发展,而催化剂是这种方法制备碳纳米材料的关键因素。目前除了传统的单元Fe、Co和Ni及其合金催化剂,人们正在努力研究更加高效的新型催化剂如引入助剂合成多元催化剂等,用来制备结构和形貌更加完美的碳材料以及更加适合于各个领域实际应用的碳纳米材料。水滑石作为一种层状结构材料,其层板上的金属阳离子在种类和组成上具有可调变性,而且金属离子在层板上分布具有整体均匀性,因此利用水滑石前体可以得到高分散的金属离子,经过焙烧或者还原可以得到高度分散粒径均匀的金属粒子。本论文分别利用成核晶化隔离法、动态尿素法等方法制备得到一系列不同层板阳离子组成的NiTi-LDHs以及CuNiCrSn-LDHs,将CuNiCrSn-LDHs经过高温焙烧得到CuNiCrSn-LDOs,利用所得的NiTi-LDHs和CuNiCrSn-LDOs分别催化乙炔分解制备得到不同结构和形貌的碳材料,利用XRD、TG-DTA和SEM对其进行表征。然后利用电化学沉积法在上述碳材料表面沉积贵金属Pt制备得到电催化剂Pt／碳材料应用于甲醇的电催化氧化研究,考察其电催化性能以及抗中毒性能,实验证明其电催化活性和稳定性都高于商业化的Pt／C电极。利用原位生长技术在γ-Al2O3表面制备得到NiAl-LDHs/γ-Al2O3,并将此水滑石直接用于催化乙炔气体分解生长碳材料,系统研究了前体不同制备方法、不同Ni含量以及催化生长碳材料时间等对所生长碳材料结构、形貌和产量等的影响,并研究在NiAl体系中引入Mg、Cu等金属元素制备得到多元负载型水滑石结构对碳材料结构和形貌的影响,最终分别得到了碳纳米管和螺旋形碳纤维等多种形貌的碳材料,可以通过调节催化剂前体中金属种类及组成来控制所得碳材料的形貌。分别使用了XRD、SEM、TEM、HRTEM、Raman和TG-DTA等分析手段对所得碳材料进行表征。并初步探索这种负载型催化剂的可重复利用性,运用简单的超声或者搅拌等物理手段将所得碳材料与载体分离,载体上保留的催化剂组分仍可以继续用于催化生长碳材料。更多还原

【Abstract】 As combination of carbon materials and nano-materials, carbon nanotubes and carbon nanofibers have many unique physical and chemical properties. Based on these properties, many potential applications have been proposed for them, including composite reinforced materials, adsorption, hydrogen storage, field emission, catalysts and catalysts carriers, lithium-ion batteries, sensors, new blended and muscle materials, electronic probes and other areas. With the deepening of researchers’detailed work, carbon nanotubes and carbon nanofiber will have more application prospects.Among tens of synthesis methods for these carbon nanomaterials, the thermal chemical vapor deposition (CVD) method attracts more attention and has rapid development in low cost and high efficiency. The catalysts play a crucial role in the CVD process. In addition to the traditional catalysts like Fe, Co, Ni and their alloy, researchers have explored some new catalysts to synthesize carbon nanomaterials with more perfect structures and morphologies or more suitable for practical applications in more areas. It has been found that the basic nature of the exchangeable property of cation in the brucite layer of LDHs and in-situ transformation to composite metal oxides is useful for metal dispersion which is responsible for many potential applications. So the LDHs and the calcined productors LDOs can be used as catalysts and catalysts carriers for metal dispersion becomingly.In this work, we have synthesized NiTi-LDHs and CuNiCrSn-LDHs with different metal ratios. And using the NiTi-LDHs and calcined products of CuNiCrSn-LDHs as catalytic precursors, various morphologies of carbon nanostructures can be produced. The materials have been characterized by XRD, SEM, TG and CV tests. The electrocatalitic activity of the electrodes of Pt particles deposited on the as-grown carbon nanostructures has been attested to be excellent for methanol oxidation.We have synthesized NiAl-LDHs/γ-Al2O3 in y-Al2O3 using in-situ growth method. Carbon nanostructures have been prepared using these LDHs. We have done system exploration and research of effects of different Ni content, precipitation agents for the preparation of LDHs and catalytic time on the structures, morphologies and yield of the carbon nanostructures. And with the introduction of Mg and Cu to NiAl-LDHs/γ-Al2O3, we have investigated the catalyst components’influence on the morphologies of the carbon nanostructures produced by those LDHs. We have attained carbon nanotubes, coiled carbon nanotubes and carbon nanofiber and helical cabon nanofibers and so on. The carbon materials were characterized using XRD, SEM, TEM, Raman and TG-DTA. The supported catalysts have been attested to be reused to catalytic reaction expediently.更多还原