Mg(NH_2)_2的合成以及Mg(NH_2)_2-LiH的储氢性能研究  

Synthesis of Mg(NH_2)_2 and Hydrogen Storage Properties of Mg(NH_2)_2–LiH System

作　　者：赵晓宇[1] 张轲[1] 曹中秋[1] 鲁杰[1] 张洪波[1] 辛士刚[1] 张辉[1] 

机构地区：[1]沈阳师范大学,辽宁沈阳110034

出　　处：《稀有金属材料与工程》2014年第2期395-398,共4页Rare Metal Materials and Engineering

基　　金：国家高技术研究发展计划专题课题("863")(2009AA05Z105);沈阳师范大学实验中心主任基金(sy2x1002)

摘　　要：通过机械球磨的方法，将MgH2粉末与高纯NH3球磨反应后在300℃下热处理晶化，制备出了高纯度的Mg（NH2）2。在150~240℃的温度范围内，对MgCNH2）2＋2．2LiH（摩尔比）储氢体系的储氢性能进行了研究，结果发现，在系统脱氢后的产物为Li2Mg（NH）2。放氢动力学揭示了该系统在200~240℃时可逆储氢量可达4．5％（质量分数）左右。该系统在150℃开始脱氢，在动力学数据的基础上可以计算出其活化能为51．7kJ／mol。此外，脱氢反应的焓变和熵变可由P-C-T曲线得到，其值分别为42．8kJ／molH2和149．2J．K～／molH2。Mg（NH2）2 was synthesized first by high energy milling MgH2 powder in a 99.995% NH3 atmosphere and then via crystallization heat treating at 300℃, and the hydrogen storage properties of Mg（NH2）2＋2.2LiH （molar ratio） were investigated in the temperature range of 150-240 ℃. It is found that mechanical milling of Mg（NH2）2 and LiH with molar ratio 1：2.2 followed by heat treatment under static hydrogen pressure and dehydrogenating at 208.5 ℃ yields the desired reversible hydrogen storage phase：Li2Mg（NH）2. Desorption kinetics reveal that the reversible hydrogen capacity for the system can reach 4.5wt% in the temperature range of 200-240 ℃.The system starts to dehydrogenate at 150℃ and the Arrhenius activation energy Ea of desorption reaction can be determined to be 51.7 kJ/mol H2 based on the data of kinetics. Additionally, the dehydrogenating reaction enthalpy （△H） and entropy （△S） are calculated to be 42.8 kJ/mol H2 and 149.2 J.K^-1/mol H2, respectively, by P-C-T measurements.

关 键 词：Mg(NH2)2 Mg-Li-N-H储氢材料 P-C—T曲线 吸放氢动力学 

分 类 号：TB34[一般工业技术—材料科学与工程]