Ti掺杂的MgH2和Mg2NiH4的放氢性能  

Hydrogen Desorption Performance of Ti-Mediated MgH_2 and Mg_2NiH_4

作　　者：周广有[1] 郑时有[1] 方方[1] 张晶[1] 徐芬[2] 孙立贤[2] 陈国荣[1] 孙大林[1] 

机构地区：[1]复旦大学材料科学系,上海200433 [2]中国科学院大连化学物理研究所,大连116023

出　　处：《化学学报》2008年第9期1037-1041,共5页Acta Chimica Sinica

基　　金：国家自然科学基金(No.10776004);上海市科学技术委员会(No.0652NM028);上海市重点学科建设(No.B113)资助项目

摘　　要：以TiF3和Ti(OBu-n)4为催化剂,研究了Ti离子掺杂对MgH2和Mg2NiH4放氢性能的影响.结果表明,未掺杂的MgH2起始放氢温度为420℃,掺杂TiF3和Ti(OBu-n)4后分别降低到360和410℃;Mg2NiH4在掺杂TiF3后放氢温度由230℃降低到220℃,而掺杂Ti(OBu-n)4后没有变化.可见无论对MgH2或Mg2NiH4,在降低放氢温度方面TiF3都明显优于Ti(OBu-n)4.另外,研究还发现,TiF3掺杂对MgH2放氢动力学有显著的提高,但对Mg2NiH4没有明显的提高.结合XRD和FTIR的测试分析,我们认为:催化作用很大程度上取决于氢化物自身的晶体结构和催化剂的电子结构;降低氢化物放氢温度和提高动力学性能的原因是催化剂与氢化物之间的相互作用削弱了氢化物中Mg—H或Ni—H键,使得活泼的H…H原子对容易形成,从而有利于H2的释出.TiF3 and Ti（OBu-n）4-doped MgH2 and Mg2NiH4 were investigated with regard to hydrogen desorption performance. It was found that the onset temperature for hydrogen release was around 420 ℃ for the blank MgH2, but decrease to 360 and 410 ℃ for the TiF3- and the Ti（OBu-n）4-doped MgH2, respectively. For Mg2NiH4, it was reduced from 230 to 220 ℃ after doping with TiF3, but remained unchanged once doping with Ti（OBu-n）4. These indicate that TiF3 is more efficient than Ti（OBu-n）4 in reducing the stability of MgH2 and Mg2NiH4. The enhanced desorption kinetics is attained in the TiF3-doped MgH2, but not in the TiF3-doped Mg2NiH4. Combined with XRD and FTIR techniques, the catalytic activity was thought to be jointly influenced by the crystal structure of the hydride and the electronic structure of the catalyst. The decrease in hydrogen release temperature and the improvement in kinetics are owing to the weakening of the Mg（Ni）--H bonds through the interactions between the catalyst and the hydride, thus facilitating energetically the formation of intra-H…H pairings that further recombine readily towards the molecular hydrogen.

关 键 词：Ti掺杂 放氢性能 MgH2 MG2NIH4 

分 类 号：TB34[一般工业技术—材料科学与工程]