摘要
为了降低MgH2的吸放氢温度,提高其吸放氢动力学性能,本文通过球磨方法制备了MgH2+20%(w)MgTiO3复合储氢材料,并研究了其储氢性能.X射线衍射(XRD)结果表明,MgTiO3在与MgH2球磨过程中生成Mg2TiO4和TiO2,并且Mg2TiO4和TiO2在体系的吸放氢过程中保持稳定,能够对MgH2的吸放氢过程产生催化作用.程序升温脱附和吸/放氢动力学测试结果表明,添加MgTiO3后MgH2的初始放氢温度从389°C降至249°C.150°C下的吸氢量从0.977%(w)提高到2.902%(w),350°C下的放氢量从2.319%(w)提高到3.653%(w).同时,MgH2放氢反应的活化能从116kJ·mol-1降至95.7kJ·mol-1.与MgH2相比,MgH2+20%(w)MgTiO3复合材料的热力学与动力学性能均有显著提高,这主要是由于球磨和放氢过程中原位生成的TiO2和Mg2TiO4具有良好的催化活性.
With the aim of decreasing the dehydriding temperature and improving the hydriding/dehydriding kinetic properties of MgH2, we prepared MgH2＋20%（w） MgTiO3 composite via bal-mil ing, and investigated the hydrogen storage properties of the composite. X-ray diffraction （XRD） results showed that the MgTiO3 decomposed into Mg2TiO4 and TiO2 during the bal-mil ing. These two resulting compounds remained stable during the hydriding/dehydriding processes, working as catalysts for the hydriding/dehydriding. Temperature-programmed-desorption （TPD） and hydriding/dehydriding kinetics tests showed that doping MgH2 with MgTiO3 lowered the onset dehydrogenation temperature of MgH2 from 389 to 249 ＆#176;C, as wel as increasing the hydrogen absorption amount from 0.977%（w） to 2.902%（w） at 150 °C, and increasing the desorption amount from 2.319%（w） to 3.653%（w） at 350 ＆#176;C. The MgTiO3 additive decreased the dehydriding activation energy of MgH2 from 116 to 95.7 kJ·mol-1. The thermodynamic and kinetic performance of the MgH2＋20%（w） MgTiO3 composite was significantly improved compared with pristine MgH2, which was attributed to the high catalytic activity of the （in-situ formed） TiO2 and Mg2TiO4 during the bal-mil ing and dehydriding processes.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2014年第12期2323-2327,共5页
Acta Physico-Chimica Sinica
基金
The project was supported by the National Natural Science Foundation of China(50971112,51001043)
Scientific Research Projects in Colleges and Universities in Hebei Province,China(ZD2014004)~~
