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研究了Ca(AlH_4)_2机械力化学合成过程的反应机理及添加K_2TiF_6,KBF_4,TiF_3,NbF_5对其放氢过程的影响.结果表明,机械球磨过程中,LiAlH_4与CaCl_2先反应形成中间相LiCa(AlH_4)_3,中间相再与CaCl_2反应生成Ca(AlH_4)_2.添加含F~-化合物可有效改善Ca(AlH_4)_2的放氢性能,其中,K_2TiF_6的催化效果最佳,可使Ca(AlH_4)_2前两步放氢温度分别降低39和66℃.含F~-化合物在球磨或加热过程中与Ca(AlH_4)_2发生化学反应,产物可催化Ca(AlH_4)_2放氢过程.
The mechanism of mechanical chemical synthesis of Ca (AlH 4) 2 and the effect of addition of K 2 TiF 6, KBF 4, TiF 3 and NbF 5 on the hydrogen evolution were investigated. The results show that LiAlH 4 and CaCl 2 react first to form LiCa AlH_4) _3, the mesophase reacts with CaCl_2 to form Ca (AlH_4) _2. The addition of F_ (-) compounds can effectively improve the hydrogen desorption performance of Ca (AlH_4) _2. The catalytic effect of K_2TiF_6 is the best, ) _2 The first two steps of desorption temperature were reduced by 39 and 66 ℃ respectively.The chemical reaction of F ~ - containing compounds with Ca (AlH_4) _2 during ball milling or heating could catalyze the Ca (AlH_4) _2 desorption.