纯Ti(BH_4)_3·5NH_3的制备及储氢性能

The Preparation and Hydrogen Storage Properties of Pure Ti(BH_4)_3·5NH_3

氨合硼氢化钛是一类放氢温度适宜的高容量储氢材料,但已报道的通过球磨法制备的氨合硼氢化钛通常含有质量分数42%以上的LiCl杂质,降低了体系总含氢量的同时也为氨合硼氢化钛本征放氢性能的表征带来了困难.因此,纯氨合硼氢化钛的制备和性能表征十分必要.本文以钛酸四异丙酯、乙硼烷、四氢呋喃和NH_3为初始原料,通过先制备前驱体Ti(BH_4)_3·2THF,然后再氨化的二步反应首次成功合成纯Ti(BH_4)_3·5NH_3,并对前驱体和氨合硼氢化钛的组成、结构和放氢性能进行系统地研究.结果表明,前驱体Ti(BH_4)_3·2THF属于斜方晶系,Pbcn空间群,且在室温下能稳定存在,是制备氨合硼氢化钛的良好前驱体;纯Ti(BH_4)_3·5NH_3具有良好的放氢性能,于75℃开始放氢,至200℃释放质量分数约10%的氢气.

Ammine titanium borohydride,with suitable dehydrogenation temperature and high hydrogen content,is considered one of the promising hydrogen storage materials.However,the existing preparation method（ball milling ammine titanium borohydride and lithium borohydride）suffers from the high content of LiCl impurities,which are difficult to be removed and not only reduces the total hydrogen content of the system but also hinders the study of its intrinsic hydrogen storage properties.Therefore,the preparation of pure ammine titanium borohydride and the study on its hydrogen storage performance are necessary and urgent.In this paper,pure Ti（BH4）3 ·5NH3 was successfully synthesized through a two-step reaction：first,precursor Ti（BH4）3·2THF was prepared by the reaction of tetrakisopropyl titanate （Ti（OC3H7）4） and diborane （B2H6） in tetrahydrofuran（THF）;then pure Ti（BH4）3·5NH3 was synthesized by reacting Ti（BH4）3·2THF and NH3.The composition,structure and hydrogen release properties of these products were systematically studied.Results show that,Ti（BH4）3·2THF has a orthorhombic structure with space group Pbcn,and is stable at room temperature,which is a favorable precursor for the preparation of Ti（BH4）3·5NH3.Pure Ti（BH4）3·5NH3 startes to release hydrogen at approximately 75℃,and released more than 10%（w）hydrogen below 200℃.