(南京工业大学 材料科学与工程学院，南京 210009)
摘 要: 采用机械球磨法在LiAlH4+MgH2体系中添加不同种类催化剂，以提高复合体系的放氢性能。运用XRD、SEM、EDS、XPS以及Sieverts法研究复合体系的结构以及放氢性能，并探讨TiF3 的催化机理。结果表明：TiF3催化剂的添加显著降低了复合体系的起始放氢温度，提高了放氢动力学性能，该体系在84.1 ℃开始脱氢，放氢量(质量分数)达8.0%。热脱附过程中TiF3参与了反应，并生成含Tix+的未知化合物，有效地促进了LiAlH4和MgH2之间的协同放氢。复合体系掺杂TiF3后，其热脱附反应的活化能Ea为79.1 kJ/mol，与未添加TiF3的复合体系的活化能(91.3 kJ/mol)相比，TiF3的添加极大地降低了放氢反应动力学势垒。
关键字: LiAlH4；MgH2；TiF3；催化机理
（College of Materials Science and Engineering, Nanjing University of Technology, Nanjing 210009, China）
Abstract:The LiAlH4+MgH2 composites doped with different catalysts were prepared by mechanical milling to improve the hydrogen desorption properties. Structural and dehydrogenation properties of the composites were investigated by XRD, SEM, EDS, XPS and Sieverts method. The catalytic mechanism of TiF3 was also discussed. The results show that doping with TiF3 decreases effectively the onset hydrogen desorption temperature, and increases the dehydrogenation kinetics of the composite. The TiF3-doped system exhibits the onset hydrogen desorption temperature of 84.1 ℃ and hydrogen desorption capacity (mass fraction) of 8.0%. The unknown Tix+-containing compound forms during thermal desorption of the composite, which promotes effectively the synergetic dehydrogenation of LiAlH4 and MgH2. In addition, the dehydrogenation activation energy Ea of the composite doped with TiF3 is calculated by JMA equation to be 79.1 kJ/mol, which is much lower than that of the composite without TiF3 addition (91.3 kJ/mol), indicating that TiF3 addition decreases greatly the kinetic barrier for dehydrogenation.
Key words: LiAlH4; MgH2; TiF3; catalytic mechanism
