机械球磨固相化学反应制备AlH_3

Preparation of AlH_3 with mechanical ball-milling solid-phase chemical reaction

以LiAlH4和AlCls为原料，采用机械球磨固相化学反应方法合成铝氢化合物，通过XRD、TG-DSC和MS等方法对反应产物进行分析和表征，研究不同球磨时间对球磨反应体系合成产物的转变规律和对产物热力学性能的影响．结果表明，随着球磨时间的增加，合成反应按3LiAlH4＋AlC23→4AlH3＋3LiCl方向进行并形成了非晶态铝氢化合物（AlH4），球磨20h时反应基本完全．球磨产物的放氢失重温度主要集中在100～200℃，对应的DSC曲线在135℃和165℃出现2个放热峰，随球磨时间的增加，失重量减少，最大失重质量分数达到3．5％～6．1％．球磨过程中形成的反应产物LiCl·H2O及少量AlH3发生分解是影响球磨反应产物最大失重量的主要因素．

Synthesis of AlH3 with LiAlH4 and AlCl3 was conducted by using bail-milhng sollct-pnase chemical reaction. The reaction resultant was analyzed and characterized, and the effect of milling time on the transformation pattern of the synthesized resultants of the ball-milling reaction system and thermody- namic properties of the milled composites were investigated by using X-ray diffraction （XRD）, thermal a- nalysis （TG-DSC）, and mass spectrum （MS）. It was found that the ball-milling reaction took the course of 3LiAlH4 ＋AlCl-4AlH3＋3LiCl to generate amorphous hydrogen-aluminum compound （AlH3）, in which the reaction was almost complete after milling for 20 h. The temperature of hydrogen-releasing and weight- losing was in the region of 100～200℃ and there were two exothermic peaks observed at 135 ℃ and 165 ℃ on their corresponding DSC curve. With the increase of milling time, the weight-losing was further de- creased and the maximum lost weight attained to 3. 5 % - 6. 1%. The main reason of great weight-losing was the decomposition of a few AlH3 and as well as the reaction resultant--LiCl ·H2O formed during the milling process.