NaAl(NH2)4的热解过程研究

The pyrolysis process of NaAl(NH2)4

摘要:

本文旨在研究Al-N-H潜在储氢体系，通过NaAl(NH2)4的热解过程研究分析该物质作为储氢材料的可行性。首先，实验通过NaAlH4与液氨反应成功制备出 NaAl(NH2)4，并利用XRD与FT-IR对其进行了表征。其次，通过热分析、XRD、FT-IR以及对制备样品不同温度热处理产物物相分析等方式对NaAl(NH2)4的热解过程进行了研究，实验结果表明：NaAl(NH2)4在68℃时开始缓慢发生分解放出NH3，250℃时热解基本完成，共放出约2倍摩尔量的NH3。中间产物NaAl(NH)2为非晶态，并在113.8 ℃左右发生分解。NaAl(NH2)4中[NH2]? - Al键，N-H键均为共价键，热解过程，[NH2]? -Al键先行断裂从而生成NH3，NaAl(NH2)4最终热解产物为NaNH2、AlN并伴随NH3的生成。

Abstract:

In this paper, the NaAl(NH2)4 phase is successfully prepared from NaAlH4 reacting in liquid ammonia at low temperature, and the XRD pattern and FT-IR was used to the characterization. The decomposition process of the NaAl(NH2)4 were studied By thermoanalysis, XRD pattern and FT-IR, and product analysis of as-prepared samples at different temperature heat treatment. The experiments show that: The thermal decomposition of NaAl(NH2)4 under primary vacuum leads to the release of NH3 and completed at 250癈 with Two moles of NH3 released. Meanwhile, intermediate NaAl(NH)2 was amorphous and decomposed at about 113.8 ℃. In the complex NaAl(NH2)4, [NH2]? is covalently bonded with Al, and the same to N-H bone. In the pyrolysis process, [NH2]? - Al bone prior to break up, that lead to the formation of NH3. The final pyrolysis products of NaAl(NH2)4 is NaNH2, AlN and NH3.