CAS OpenIR
铜和镍基纳米材料的制备及其在合成气转化中的应用
庄嘉豪
Subtype硕士
Thesis Advisor苏发兵
2018-07
Degree Grantor中国科学院研究生院
Degree Name硕士
Degree Discipline材料工程
Keyword有序介孔金属氧化物,镍纳米晶,合成气,甲酸甲酯,甲烷化
Abstract

纳米材料因其独特的物理和化学特性,广泛应用于能源、催化等领域。纳米材料的催化性能与材料自身的尺寸、结构以及所处的物理环境等因素密切相关。可控制备具有特定尺寸、结构的纳米材料对研究其催化性能具有重要意义。针对合成气转化领域中通常面临的催化剂活性差、易失活、活性组分作用机理不清晰等问题,本论文可控制备了一系列三元CuO-CaO-ZrO2有序介孔材料以及不同晶相的Ni纳米晶材料,并将其分别用于合成气直接制甲酸甲酯(MF)以及合成气甲烷化反应,考察了催化剂结构对其性能的影响。本论文主要研究内容及结果如下:(1)采用溶剂挥发诱导自组装的方法制备了一系列三元Cu-Ca-Zr有序介孔催化剂,并将其用于合成气直接制甲酸甲酯反应,考察了有序介孔结构以及CuO活性组分的分散状态对催化剂活性与稳定性的影响。与浸渍法和纳米颗粒负载法制备的催化剂相比,“一锅法”制备的有序介孔催化剂表现出更高的活性和稳定性。这是因为“一锅法”制备的催化剂具有更高的比表面积,暴露出更多的活性位点,有利于CO的转化;同时,CuO高度分散于有序介孔骨架中,使CuO与CaO-ZrO2载体之间的协同效应得到增强,有利于提高MF选择性;另外,CuO与载体间较强的相互作用则有效抑制了活性组分的流失。(2)采用溶剂热的方法,以Ni(acac)2为前驱体、DMF为溶剂和还原剂、聚乙烯亚胺为表面活性剂,通过调控反应物浓度及反应时间等条件制备了具有常见的面心立方晶相(fcc)以及不常见的六方密排晶相(hcp)的Ni纳米晶。表征结果显示,立方晶相的Ni为正二十面体结构,六方晶相的Ni为六棱柱结构。并对纳米晶的生长机理进行了初步探讨。本论文首次将hcp晶相的Ni用于CO甲烷化反应,考察了晶相对催化性能的影响。催化结果表明,六方晶相的Ni表现出更高的催化活性与抗烧结性能,这是因为六方晶相的Ni存在独特的“自发分散”的现象以及其表面原子具有更高的配位不饱和度。;Nanomaterials with excellent physical and chemical properties have triggered great interest and have played a significant role in fields such as energy and catalysis. The catalytic activity of nanomaterials highly depends on their size, structure and morphology. Controlled synthesis of nanomaterials plays an important role in revealing the relationship between structure and catalytic performance. Poor catalytic performance and unclear mechanism of reaction form an obstacle in syngas conversion to methyl formate (MF) and methane. To solve these problems, ordered mesoporous CuO–CaO–ZrO2 catalysts for synthesis of methyl formate (MF) and Ni nanocrystal for methanation were synthesized, respectively. The specific findings include: (1) In order to reveal how the ordered mesoporous structure and distribution of Cu species impact the activity and the stability, a series of multicomponent Cu–Ca–Zr oxide catalysts with ordered mesoporous were synthesized by evaporation–induced self–assembly (EISA) method and used for direct synthesis of MF from syngas. The results indicate that the catalyst prepared by one–pot EISA method, in which the CuO species are highly dispersed in frame of CaO–ZrO2, exhibits better activity and stability as compared with the other two catalysts prepared by impregnation or nanoparticle immobilization method with most of CuO located on the outer surface of the CaO–ZrO2 support, because of its high specific area, the synergistic effect of two activity sites and the stronger interaction between the support and CuO active constituent. (2) Icosahedral Ni nanocrystals with face centered cubic (fcc) crystal structure and hexagonal prisms with hexagonal close packed ( hcp ) phase were prepared by solvothermal method and by using Ni(acac)2 as precursor, N, N-dimethylformamide (DMF) as the reducing agents and solvents and polyethyleneimine (PEI) as surfactant. The possible growth process is proposed by controlling reaction time. We first use the hcp Ni in the reaction of CO methanation and investigate the effect of Ni crystalline phase on its catalytic performance. The results show that Ni particles with hcp phase possess enhanced catalytic activity and anti-sintering ability compared with fcc Ni, because of its “self-abruption” effect and low coordination of surface Ni atoms. 

Language中文
Document Type学位论文
Identifierhttp://ir.ipe.ac.cn/handle/122111/26870
Collection中国科学院过程工程研究所
研究所(批量导入)
Recommended Citation
GB/T 7714
庄嘉豪. 铜和镍基纳米材料的制备及其在合成气转化中的应用[D]. 中国科学院研究生院,2018.
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