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Mg(AlH4)2是一种理想的储氢材料,理论储氢容量高达7.5%(质量分数)。然而较高的起始放氢温度在很大程度上制约了Mg(AlH4)2的应用。正交试验设计方法能够在较少的试验次数中掌握可靠的实验数据以及各因素之间的内在联系从而确定最优的实验方案,特别适用与多因素多水平的实验条件研究。利用高能球磨法成功地制备了Mg(AlH4)2,并将NaAlH4和TiF3引入到该体系中。利用傅里叶红外转换测试仪(FTIR)对产物的结构进行表征,程序控温脱附(TPD)对产物的放氢温度和放氢量进行测定。此外,采用三因素三水平的L9(33)正交试验法,以Mg(AlH4)2的起始放氢温度为指标,以NaAlH4的添加量、TiF3的添加量和球磨间隔时间为因素,同时考察以上3项重要因素对降低Mg(AlH4)2起始放氢温度的影响。通过对正交试验的系统分析发现,NaAlH4的添加量对降低Mg(AlH4)2的起始放氢温度影响最显著,其次为TiF3的添加量,最后为球磨间隔时间。得到最佳试验条件,在最佳条件下Mg(AlH4)2的起始放氢温度仅为72℃,与未添加的相比放氢温度降低了67℃,放氢性能明显提高。
Mg (AlH4) 2 is an ideal hydrogen storage material, the theoretical hydrogen storage capacity of up to 7.5% (mass fraction). However, the higher initial hydrogen evolution temperature restricts the application of Mg (AlH4) 2 to a great extent. Orthogonal experimental design method can determine reliable experimental data and the inherent relationship among various factors in a small number of experiments to determine the optimal experimental scheme, especially for multi-factor and multi-level experimental conditions. Mg (AlH4) 2 was successfully prepared by high energy ball milling and NaAlH4 and TiF3 were introduced into the system. The structure of the product was characterized by Fourier transform infrared spectroscopy (FTIR). The programmed temperature-controlled desorption (TPD) was used to determine the product hydrogen desorption temperature and hydrogen desorption capacity. In addition, using the three factors and three levels of L9 (33) orthogonal test, taking the initial hydrogen desorption temperature of Mg (AlH4) 2 as an index, the factors of adding amount of NaAlH4, adding amount of TiF3 and ball milling interval, The effect of the above three important factors on reducing the initial hydrogen evolution temperature of Mg (AlH4) 2 was investigated. Through systematic analysis of orthogonal experiment, it is found that the addition of NaAlH4 has the most significant effect on reducing the initial hydrogen evolution temperature of Mg (AlH4) 2, followed by the addition of TiF3 and finally the ball milling interval. Under the optimal conditions, the initial hydrogen desorption temperature of Mg (AlH4) 2 was only 72 ℃, and the desorption temperature was reduced by 67 ℃ compared with the unadded one. The hydrogen desorption performance was obviously improved.