氨基络合物制备氨硼烷及放氢性能研究

摘要

This paper reports on the synthesis of ammonia borane（NH3BH3,AB） from sodium borohydride and ammonia complex Ni（NH3）6？Cl2 and the dehydrogenation of the as-synthesized AB.The composition and purity of the products have been tested by instrumental analyses of XRD,FTIR,11B NMR and ICP.The effects of raw materials molar ratio,reaction temperature,reaction time and solvent on the synthesis of AB have been systematically investigated.At the same time,a thermal decomposition process has also been ex-plored on the as-prepared AB with different raw material ratios.The results show that a pure phase AB（pu-rity99%） can be obtained with the molar ratio of NaBH4∶Ni（NH3）6Cl2=2∶1 and the reaction time of 10 h.Thermal analysis displays that the hydrogen gas is released in the first step from AB with raw material molar ratio of NaBH4∶Ni（NH3）6Cl2=3∶1,and impurities of diborane（m/e=27）,borazine（m/e=80） are effectively inhibited at the heating rate of 2 ℃/min.In addition,a certain amount of Ni nanoparticles with the size of about 10 nm exist in the products,which would be used as a catalyst for the hydrolysis of AB.%以NaBH4为硼源、氨基络合物Ni（NH3）6Cl2为氨源制备高储氢容量的氨硼烷（NH3BH3,Ammonia Borane,AB）及其放氢性能研究.通过XRD,FTIR,11B NMR,ICP等手段分析表征了所制备产物的组成和纯度,在此基础上探究了原料比例、反应温度、时间和溶剂等因素对产物的影响.同时,对不同原料比制得氨硼烷的热解放氢性能进行了研究.实验结果表明：当物质的量NaBH4∶Ni（NH3）6Cl2=2∶1经过10 h的反应,得到了纯度非常高的氨硼烷（纯度〉99%）;以NaBH4∶Ni（NH3）6Cl2=3∶1得到的氨硼烷,当以2℃/min进行升温时,氢气释放主要集中在第一步,并且没有硼烷和硼嗪等杂质气体的产生.另外,在产物中得到了金属Ni纳米颗粒,经洗涤干燥后其粒径大小可控制在10 nm左右,在催化氨硼烷等材料的水解放氢方面具有潜在的应用价值.