“Multi-Yolk-Shell”Bi@C中空复合结构的合成及催化RDX的热分解研究

发布时间：2018-02-12 09:12

本文关键词： Bi@C Multi-Yolk-Shell 中空结构柯肯达尔黑索金催化　出处：《西北大学》2015年硕士论文　论文类型：学位论文

【摘要】：本论文通过还原性葡萄糖与硝酸铋在水热条件下一锅反应,制备出新颖的Bi@C复合纳米结构,并借助X-射线粉末衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、X-射线光电子能谱(XPS)、X-射线能谱(EDX)和拉曼光谱(RS)等测试方法对其形貌、结构及组分进行表征。结果表明,产物Bi@C是由厚度为100 nm且表面富含-OH、C=O和-COOH等功能基团的碳层包覆多个粒径约80 nm的金属Bi球的"Multi-Yolk-Shell"复合中空结构,其颗粒的整体尺寸约600 nm。通过改变反应原料中加入葡萄糖的量可以有效控制产物碳层的厚度及碳壳内Bi球的数目。为了研究Bi@C的形成机理,进行了一系列控制反应时间的实验,采用XRD、TEMSEM对Bi@C在不同反应阶段的形貌、结构及组分变化进行仔细分析,发现在中空Bi@C结构的形成过程中受到柯肯达尔(Kirkendall)效应的影响,即由Bi3+与葡萄糖形成的过渡态的核(TSC)由内向外扩散的速率大于功能性碳质粒子由外向内扩散的速率,这种扩散的不平衡导致空位的形成,进而发生Kirkendall空化过程。另外,被还原的单质Bi微粒在碳壳内自发成核生长,最终形成“Multi-Yolk-Shell" Bi@ C复合中空结构。通过差示量热扫描仪(DSC)分析环三次甲基三硝胺(黑索金,RDX)在加入不同量Bi@C及不同升温速率下燃烧热分解的情况,并分别用Kissinger和 Ozawa法计算其表观活化能(Ea)和指前因子(A)等动力学参数来研究Bi@C对RDX热分解的催化性能。结果显示,Bi@C具有很高的燃烧催化性能,能够显著提高RDX的燃烧速率,可以将其热分解的峰温(Tp)显著提前,并能很大程度降低其燃烧时的表观活化能(Ea)。
[Abstract]:In this paper, novel Bi@C nanostructures were prepared by the one-pot reaction of reducing glucose and bismuth nitrate under hydrothermal conditions. The morphology, structure and composition were characterized by means of X-ray powder diffraction (XRDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy (RS), etc. The morphology, structure and composition of the samples were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy (RS). The product Bi@C is a "Multi-Yolk-Shell" composite hollow structure coated by a carbon layer with a thickness of 100nm and rich functional groups such as -OHH Con O and -COOH on the surface of Bi spheres with a diameter of about 80 nm. The whole size of the particle is about 600 nm. The thickness of carbon layer and the number of Bi spheres in carbon shell can be effectively controlled by changing the amount of glucose in the raw material. In order to study the formation mechanism of Bi@C, a series of experiments have been carried out to control the reaction time. The morphology, structure and component changes of Bi@C at different reaction stages were analyzed by using XRDX TEMSEM. It was found that the formation of hollow Bi@C structure was affected by Kirkendall effect. That is, the transition state formed by Bi3 and glucose diffuses more rapidly from inside to outside than from outside to inside of functional carbon particles. The imbalance of diffusion leads to the formation of vacancies and the process of Kirkendall cavitation. The reduced Bi particles spontaneously nucleate and grow in the carbon shell. Finally, the "Multi-Yolk-Shell" Bi@C composite hollow structure was formed. The combustion thermal decomposition of ring trimethylene trinitramine (RDX) was analyzed by differential calorimetry (DSC) under different Bi@C and different heating rates. The kinetic parameters such as apparent activation energy (EA) and preexponential factor (A) were calculated by Kissinger and Ozawa, respectively, to study the catalytic performance of Bi@C for RDX thermal decomposition. The results show that Bi@C has high combustion catalytic performance and can significantly increase the combustion rate of RDX. The peak temperature T _ p of its thermal decomposition can be significantly advanced and the apparent activation energy of its combustion can be reduced to a great extent.
【学位授予单位】：西北大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB33

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