新型非贵金属Fe、Ni基纳米催化剂的结构调控与催化制氢性能

发布时间：2018-04-15 21:23

本文选题：氨分解 + 氨硼烷水解　；参考：《华东理工大学》2017年硕士论文

【摘要】：氢能来源丰富、可再生和可储存的优点,使其成为未来替代化石燃料的理想能源之一。寻求高密度储氢材料和研发高效非贵金属催化剂来建立洁净氢能系统已成为当前能源研究的热点之一。氨气和氨硼烷均具有较高的能量密度(氢密度分别为17.6wt%和19.6wt%),且易储存运输,故而两种储氢材料均成为了人们关注的对象。高效氨分解和氨硼烷水解制氢催化剂主要集中于贵金属催化剂(如Ru、Pt),高昂的成本迫使人们开发低成本和高储量的非贵金属催化剂(如Fe、Ni、Co)。此外,氨分解和氨硼烷水解作为典型的结构敏感性反应,不仅广泛应用于洁净能源的转化,还可以用作模型反应体系来研究催化剂表面结构、电子特性与催化性能之间的关系。本文以Fe、Ni基非贵金属催化剂为研究对象,采用催化化学气相沉积(Catalytic Chemical Vapor Deposition,CCVD)法和液相化学还原法分别制备可控形貌的Fe基催化剂和Ni基复合物催化剂,并应用于氨分解和氨硼烷水解制氢模型反应,阐明催化剂结构和制氢反应性能的构效关系。(1)研究了碳源分压和纳米碳纤维生长时间在CCVD过程中对Fe纳米颗粒形貌调控的影响。发现碳源分压较高时有利于形成长状多面体形貌的Fe颗粒,碳源分压较低时易形成无规则形貌的Fe颗粒。碳纤维生长时间的增长则会进一步导致Fe纳米颗粒的重构。多面体形貌的Fe纳米颗粒表现出更高的氨分解活性。(2)比较研究了CCVD法和传统浸渍法制备的Fe、Ni基催化剂的氨分解活性,发现两种方法制备的催化剂活性趋势相反。进一步结合理论计算,揭示了表面C和次表面C对Fe、Ni催化剂上氨分解性能的影响机制,发现其影响规律呈现出相反的趋势。(3)利用化学还原法制备了 NiB非晶态合金及其载体复合物催化剂并考察其在氨硼烷水解制氢中的活性和耐久性。进一步利用N2-BET、XRD、TEM等催化表征手段分析了不同催化剂的载体效应。动力学和同位素实验表明CNTs负载的NiB非晶态合金催化剂具有较低的活化能并且能够促进水的活化,进而提高氨硼烷水解活性。
[Abstract]:Hydrogen rich source of renewable and storage advantages, make it become one of the ideal energy to replace fossil fuels in the future. For high density hydrogen storage materials and development of high efficiency non noble metal catalysts to establish clean hydrogen energy system has become a hotspot of current research. The energy of ammonia and ammonia borane have high energy density (hydrogen density respectively. For 17.6wt% and 19.6wt%), and easy storage and transportation, so the two kinds of hydrogen storage materials have become the object of attention. Efficient decomposition of ammonia and ammonia borane hydrolysis catalysts mainly concentrated on noble metal catalysts (Ru, Pt), the high cost of forcing people to develop low cost and non noble metal catalysts with high reserves (such as Fe, Ni, Co). In addition, the decomposition of ammonia and ammonia borane hydrolysis as a typical structure sensitive reaction, the transformation is not only widely used in clean energy, can also be used as model to study catalytic reaction system Agent surface structure, the relationship between the electronic properties and catalytic performance of Fe. In this paper, Ni based non noble metal catalyst as the research object, using catalytic chemical vapor deposition (Catalytic Chemical Vapor Deposition, CCVD) preparation of controllable morphology of Fe catalyst and Ni composite catalyst respectively, preparation method and liquid phase chemical reduction method. And applied to the decomposition of ammonia and ammonia borane hydrolysis hydrogen production model reaction. The relationship between structure and hydrogen production catalyst performance (1). To clarify the effects of carbon source growth time on the morphology of Fe nanoparticles in the regulation process of CCVD pressure and nano carbon fiber. It is found that the carbon source pressure is high to Fe the particles formed long shaped polyhedron morphology, carbon source at low pressure to form Fe particles of irregular shape. The growth of carbon fiber growth time would lead to the reconstruction of Fe nanoparticles. The morphology of polyhedral Fe nanoparticles Exhibit higher ammonia decomposition activity. (2) a comparative study of the CCVD method and traditional impregnation method to prepare Fe, Ni based catalysts for ammonia decomposition activity, found that the catalyst activity trend of two kinds of preparation methods of the contrary. Further according to the theoretical calculation, reveals the surface and sub surface of C C Fe, Ni catalyst ammonia decomposition performance influence mechanism, the influencing law showed the opposite trend. (3) preparation of NiB amorphous alloy and carrier complex catalyst were investigated in ammonia borane by hydrolysis of the activity and durability by chemical reduction method. The further use of N2-BET, XRD, TEM and other characterization methods of effect of different carrier catalyst the analysis of the catalyst. The kinetic and isotopic experiments show that CNTs supported NiB amorphous alloy catalyst has low activation energy and can promote the activation of water, and then improve the ammonia borane hydrolysis activity.

【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TQ116.2

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