AlH3的制备及放氢特性

以LiAlH₄, LiBH₄和AlCl₃为原料, 采用有机合成法制备了单一相的α-AlH₃和γ-AlH₃, 并对其放氢性能进行了研究.结果表明, 两种晶型AlH₃的放氢量均可达8.3%~8.5%(质量分数), 放氢温度范围在120~160℃之间, 且γ-AlH₃的放氢峰值温度比α-AlH₃低8.2℃; α-AlH₃和γ-AlH₃的放氢反应表观活化能分别为94.6和86.3 kJ/mol; 加热过程中α-AlH₃直接发生放氢反应, γ-AlH₃在放氢前先发生向α-AlH₃的相变, 这一相变过程使得AlH₃的晶格得到活化, 从而促进放氢反应的进行.

Preparations and Dehydriding Properties of AlH3

AlH₃ is a promising hydrogen storage material due to its high hydrogen capacity(10%, mass fraction) and relatively low dehydriding temperature(100—200℃). However, the complicate synthesis procedure restricts the fundamental investigation and practical application of AlH₃. In this paper, with LiAlH₄, LiBH₄ and AlCl₃ as the raw materials, pure α-AlH₃ and γ-AlH₃ were prepared and their dehydriding properties were studied. The experimental results show that the hydrogen desorption capacity of the prepared AlH₃ reaches 8.3%—8.5%(mass fraction), and the dehydriding temperature ranges from 120℃ to 160℃. The peak dehydriding temperature of γ-AlH₃ is 8.2℃ lower than that of α-AlH₃. The activation energies of dehydriding reaction of α-AlH₃ and γ-AlH₃ are 94.6 kJ/mol and 86.3 kJ/mol, respectively. During heating procedure, α-AlH₃ directly decomposes and releases hydrogen, while γ-AlH₃ transforms to α-AlH₃ before decomposition.