Na-N-B-H和Na-Ca-B-H复合体系的制备及放氢性能研究

发布时间：2018-01-16 23:11

  本文关键词：Na-N-B-H和Na-Ca-B-H复合体系的制备及放氢性能研究　出处：《北京理工大学》2015年硕士论文　论文类型：学位论文

  更多相关文章： 氨基钠 硼氢化钠 氯化钙 液相球磨 催化剂 复合材料 储氢性能

【摘要】：氢能作为一种环境友好、储量丰富、燃烧值高、可循环应用的新型能源载体,得到广泛研究,而储氢技术是目前限制氢能有效应用的关键技术瓶颈,近年来,碱金属配位氢化物储氢体系因其较高的理论储氢量和较优良的储氢性能,引发了大批学者的关注,成为国内外储氢领域研究的热点。本文在对国内外碱金属配位氢化物储氢体系研究现状和进展进行全面综述的基础上,采用液相球磨技术,以NaNH2:NaBH4(2:1)为反应物、环己烷为液相溶剂保护剂制备Na-N-B-H复合储氢材料,并在其中添加非晶态Co-Ni-B催化剂以改善材料的放氢性能。通过TG-DTA、XRD、FT-IR、活化能计算(Achar微分法和Coats-Redfern积分法)等分析测试手段对复合产物进行表征分析,以复合材料的放氢反应活化能、放氢分解温度和释氢量为主要评价指标,测试其放氢反应动力学性能和热力学性能,探讨了复合材料中催化剂添加比例对Na-N-B-H储氢材料放氢性能的影响,同时探索了由NaBH4和CaCl2通过液相球磨制备的新型Na-Ca-B-H复合材料的储氢性能。研究表明,添加5wt%Co-Ni-B的复合材料,490℃内总失重率达到5.05wt%,最接近理论储氢量,并且主要生成了新相复合物Na3(NH2)2BH4,因此确定本实验的催化剂最佳添加量为5wt%;对比添加5wt%催化剂和未添加催化剂的复合材料,前者起始放氢温度80℃、最大放氢速率峰值温度282.9℃和分解反应活化能69.1 KJ?mol-1均比后者要低,并且材料总失重率低于理论储氢量,说明放氢反应过程中催化剂抑制了杂质气体氨气的产生,提高了材料的放氢性能。同时研究表明,本实验的热解反应机理为三维扩散机理,机理函数表达式为f???=?????]1)1/(1[)1(2/313/13/4?。探索由NaBH4和CaCl2通过液相球磨制备新型Ca基储氢材料,并通过XRD、TG-DTA、活化能计算等分析方法确定了反应物制备复合材料的最佳反应比例为NaBH4:CaCl2(4:1),并研究了Na-Ca-B-H复合材料的储氢性能,结果表明,该材料起始放氢温度为145℃、最大放氢速率峰值温度为435.9℃、分解反应活化能为121.8KJ?mol-1,480℃内总失重率为2.87wt%,热解反应机理为随机成核和随后生长机理,机理函数表达式为f???=?????)]1ln()[1(4/1?3。
[Abstract]:Hydrogen energy, as a new type of energy carrier with friendly environment, rich reserves, high combustion value and recyclable application, has been widely studied. Hydrogen storage technology is the key technology bottleneck to limit the effective application of hydrogen energy in recent years. Because of its high theoretical hydrogen storage capacity and excellent hydrogen storage performance, alkali metal coordination hydride storage system has attracted a large number of scholars' attention. It has become a hotspot in the field of hydrogen storage at home and abroad. On the basis of a comprehensive review of the research status and progress of alkali metal coordination hydride hydrogen storage system at home and abroad, liquid phase ball milling technology is adopted in this paper. Na-N-B-H composite hydrogen storage material was prepared by using NaNH2: NaBH4: 1) as reactant and cyclohexane as liquid phase solvent protection agent. The amorphous Co-Ni-B catalyst was added to the catalyst to improve the dehydrogenation performance of the material. The activation energy was calculated by Achar differential method and Coats-Redfern integration method. The decomposition temperature and amount of hydrogen release are the main evaluation indexes, and the kinetic and thermodynamic properties of the hydrogen release reaction are tested. The effect of catalyst ratio on the hydrogen release properties of Na-N-B-H hydrogen storage materials was investigated. At the same time, the hydrogen storage properties of new Na-Ca-B-H composites prepared by ball milling of NaBH4 and CaCl2 were investigated. The total weight loss rate of the composite material added with 5wt Co-Ni-B at 490 鈩，

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