【作者】 张致龙；

【导师】 陈玉红；

【作者基本信息】 兰州理工大学 ， 凝聚态物理， 2011， 硕士

【摘要】 随着石油资源的日渐匮乏和生态环境的不断恶化,寻找和发展新型能源为全世界所瞩目。人们对新能源的不断探索过程中,氢能被公认为人类未来的理想能源,但氢能的储存限制了其利用。理论储氢量较大的碱金属氮化物成为储氢研究的重点,但碱金属氮化物在反应中有固—固反应,使得反应条件高,反应速率慢,反应难以充分进行。如果碱金属氮化物反应在团簇级别进行,可以降低反应条件,提高反应速度,反应更为充分。但目前在团簇级别研究碱金属氮化物的反应机理很有限。本文采用密度泛函理论（B3LYP）方法,在6-311G*基组水平上对Li₃N与H2以及团簇（Li₃N）₂与H₂反应的微观机理进行了计算分析。第一章介绍了发展氢能源的优点和主要的储备材料的研究现状,包括碳质材料、金属-有机物框架材料、金属合金材料、碱金属氮化物材料,重点介绍了Li-N-H系金属络合物储氢材料,以及碱金属氮化物团簇储氢的优点。第二章概述了量子化学的发展过程以及应用量子化学对团簇的研究方法,介绍了过渡态理论和内禀坐标理论。第三章研究了Li₃N团簇与H₂反应的微观机理,反应式为Li₃N+2H₂-Li₂NH +LiH + H₂-LiNH₂ + 2LiH,反应分两步进行,第一步为Li₃N团簇与H₂反应,第二步为Li₂NH团簇与H₂反应,优化了各步的反应物、中间体、过渡态和产物的几何构型,同时通过振动分析,结果证实了中间体和过渡态的正确性,内禀反应坐标（IRC）计算结果进一步确认了反应路径。确认了此反应为单通道放热反应。计算得到第一步反应的活化能为117.3 kJ/mol,第二步反应的活化能小于第一步仅为5.5136 kJ/mol。第四章研究了（Li₃N）₂团簇与H₂反应的微观机理,反应分两步进行,第一步为（Li₃N）₂与H₂反应,第二步为（Li₂NH）₂团簇与H₂反应,优化了反应物、中间体、过渡态和产物的几何构型,同时通过振动分析,结果证实了中间体和过渡态的正确性,内禀反应坐标（IRC）计算结果进一步确认了反应路径。确认了此反应为单通道放热反应。计算得到第一步反应的活化能为77.78 kJ/mol,第二步反应的活化能小于第一步反应为17.07 kJ/mol。更多还原

【Abstract】 With the dearth of petroleum resources and constantly deteriorating ecological environment, find and develop new energy source become a hot topic all over the world. Hydrogen energy as a new energy source, has been accepted during the process of new energy source’s find. However, the application of energy source is limited by its storage, and the alkali metal compounds which have a vast storage of hydride become a research key point. The big particles of solid are hardly adequate reaction during the reaction. Alkali metals compounds Clusters with small particles, which make the reaction can be carried through easily. The reaction mechanism of alkali metal compounds Clusters and hydrogen is paid more and more attention, and the study about this is limited now. In this paper, by means of the density functional theory （B3LYP） methods,the reaction between Li₃N and H₂, （Li₃N）₂ and H₂ have been calculated and analysis basing on the 6-311G*.In the first chapter, the advantages and the current situation of store materials of hydrogen energy has been introduced, which include carbon materials, metal- organic matter frame materials, metal alloy material, alkalis nitride and so on. Furthermore, it is emphatically introduced about the merits of Li-N-H set metal clathrate hydrogen storage material and alkalis nitride.In chapter 2, the evolution of quantum chemistry and the research method about apply quantum chemistry to cluster were summarized, and the transition state theory and intrinsic coordinate theory were introduced.Micromechanism of the reaction between Li₃N and H₂ has been studied in chapter 3. The formula of the reaction is Li₃N+2H₂ -Li₂NH +LiH + H₂-LiNH₂ + 2LiH. The geometric model of the reactions, intermediate, transition-state and products had been optimized at the same time. The correctness of intermediate and transition-state has been confirmed by the results of vibrational analysis. The pathway was calculated by IRC which has been affirmed as single channel and exothermic reaction. The calculation results indicate that the activation energy of first and second step reaction are 117.3 kJ/mol and 5.5136 kJ/mol. Comparing to the first step reaction, the second step reaction is more easy, which provides a theoretical basis for the further study of the reaction between Li₃N and H₂.In chapter 4, Micromechanism of the reaction between （Li₃N）2 Li₃N and H₂ has been studied. The formula of the reaction is Li₃N+2H₂-Li₂NH +LiH + H₂-LiNH₂ + 2LiH. The geometric model of the reactions, intermediate, transition-state and products had been optimized at the same time. The correctness of intermediate and transition-state has been confirmed by the results of vibrational analysis. The pathway was calculated by IRC which has been affirmed as single channel and exothermic reaction. The calculation results indicate that the activation energy of first and second step reaction is 77.78 kJ/mol and 17.07 kJ/mol, and the second step reaction is easier than the first. Comparing the reaction of Li₃N and H₂ to the reaction of （Li₃N）₂ and H₂,we find that the second step reaction of Li₃N and H₂ is the most easy one, and provides a theoretical basis for the further study of the reaction between （Li₃N）₂ , Li₃N and H₂.更多还原