基于Pt的纳米合金材料的合成及其催化性质研究

发布时间：2018-05-11 21:11

本文选题：贵金属 + 铂　；参考：《安徽大学》2017年硕士论文

【摘要】：贵金属纳米材料由于其在光学、力学、磁学、电学、催化和传感等领域表现出优异的物理和化学特性,受到了广泛关注。然而,由于本身性质方面的一些局限性以及十分稀少的储量,在很大程度上限制了贵金属纳米材料大规模的应用。因此,人们希望寻求一种策略,在改良贵金属纳米材料性质的同时减少贵金属的使用量。研究表明通过与其他金属形成合金,能够可控的合成特定尺寸、组成、形貌以及结构构架的金属纳米材料,并且明显的改变其如光、电、磁、催化以及机械性质等物理化学方面的性质。因此,在近些年来人们对贵金属合金纳米材料的尺寸,组成,形貌以及架构的可控合成方面进行了深入的研究。合金中不同的金属原子之间会产生相互的作用,形成特定的表面活性中心或电子结构。因为协同效应的存在,合金纳米材料往往具有优于其单一金属纳米材料的性质,同时贵金属与非贵金属形成合金也能够减少贵金属的使用降低成本费用,这非常符合工业生产降低贵金属使用量提高贵金属利用率的趋势。利用贵金属催化剂催化非均相反应,其在稳定性和循环利用方面良好的表现,也非常符合绿色化学的理念。但是在贵金属合金纳米材料应用到实际生产的过程中,依然面临着许多挑战。合成过程过于复杂、可控合成难以重复、催化机理不明确等等问题,激励着科研工作者不断的深入对贵金属合金纳米材料的研究。本文在前人的基础上,合成了基于贵金属Pt的合金纳米材料,主要对其组成、尺寸、形貌以及催化活性进行了一系列的探究:1.我们以油胺作为稳定配体,甲基-胺硼烷络合物作为还原剂,通过简单的方法合成了 AuPt合金纳米颗粒。通过高分辨透射电子显微镜、X射线衍射、电感耦合等离子体发射光谱仪等仪器进行表征。负载在CeO2上的AuPt合金纳米材料在室温常压条件下选择性催化氢化苄叉丙酮,表现出非常高的选择性和催化效率。通过分析不同Au:Pt比组成的合金纳米材料的催化表现,我们发现基于Pt原子数计算的TONPt值的变化趋势和转化率的变化趋势是非常相似的。尽管金本身在反应中并不表现出催化活性,转化率和TONPt的变化则清晰的反映出金对铂的催化活性的促进效应。在我们的实验中,非活性金属改良了活性金属的催化活性,显示了一种十分有意义的协同效应。2.Pt合金纳米材料因为其优异的性质,被广泛的应用在催化等领域。本文以油胺为保护剂配体和还原剂,在氮气保护下高温合成PtCu合金纳米颗粒,并且在空气中搅拌使空气中的氧气氧化合金中暴露在表面的Cu变为铜离子而脱离合金表面,得到具有花瓣状突起结构的PtCu合金纳米材料。实验表明,PtCu合金具有较均一的尺寸和形貌,并在催化氢化肉桂醛的反应中,表现出了良好的催化活性和选择性。
[Abstract]:Noble metal nanomaterials have attracted much attention for their excellent physical and chemical properties in optical, mechanical, magnetic, electrical, catalytic and sensing fields. However, due to some limitations of its own properties and very scarce reserves, the large-scale application of noble metal nanomaterials is limited to a great extent. Therefore, we hope to find a strategy to improve the properties of noble metal nanomaterials while reducing the use of precious metals. Studies have shown that by forming alloys with other metals, metal nanomaterials of specific size, composition, morphology, and structure can be synthesized in a controllable manner, and that they can be changed significantly, such as light, electricity, magnetism, etc. The physical and chemical properties of catalysis and mechanical properties. Therefore, in recent years, the size, composition, morphology and structure of noble metal alloy nanomaterials have been studied in detail. Different metal atoms in the alloy interact with each other to form specific surface active centers or electronic structures. Because of the synergistic effect, alloy nanomaterials tend to have better properties than their single metallic nanomaterials, and the formation of alloys between noble metals and non-precious metals can also reduce the use of precious metals and reduce costs. This is in line with industrial production to reduce the amount of precious metals used to improve the utilization rate of precious metals. The heterogeneous reaction catalyzed by noble metal catalyst has good stability and recycling performance, and it also accords with the idea of green chemistry. However, there are still many challenges in the application of noble metal alloy nanomaterials to practical production. The synthesis process is too complex, the controllable synthesis is difficult to repeat, and the catalytic mechanism is unclear, which encourages researchers to study the noble metal alloy nanomaterials in depth. In this paper, based on the previous studies, the alloy nanomaterials based on noble metal Pt have been synthesized. The composition, size, morphology and catalytic activity of the alloy nanomaterials have been investigated in a series of ways: 1. AuPt alloy nanoparticles were synthesized by a simple method using oleamine as a stable ligand and methylamine borane complex as reducing agent. It was characterized by high resolution transmission electron microscope (TEM) and inductively coupled plasma emission spectrometer (ICP-AES). The AuPt alloy nanomaterials supported on CeO2 can selectively catalyze the hydrogenation of benzylidene acetone at room temperature and atmospheric pressure, showing very high selectivity and catalytic efficiency. By analyzing the catalytic performance of alloy nanomaterials with different Au:Pt ratios, we find that the change trend of TONPt value and conversion rate based on Pt atom number is very similar. Although gold itself does not exhibit catalytic activity in the reaction, the changes in conversion and TONPt clearly reflect the catalytic effect of gold on platinum activity. In our experiments, inactive metals have improved the catalytic activity of active metals, showing a significant synergistic effect .2. Pt alloy nanomaterials have been widely used in catalysis and other fields because of their excellent properties. In this paper, PtCu alloy nanoparticles were synthesized at high temperature under nitrogen protection with oleamine as protective ligands and reductants. The Cu exposed to the surface of oxygen oxidized alloy in air was changed into copper ion and separated from the surface of the alloy by stirring in air. PtCu alloy nanomaterials with petal-like protruding structure were obtained. The results show that the PtCu alloy has a uniform size and morphology, and shows good catalytic activity and selectivity in the catalytic hydrogenation of cinnamaldehyde.
【学位授予单位】：安徽大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;O643.36

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