【摘要】 通过无压烧结法制备了固溶体MAX相(Ti_0.5V_0.5)₃AlC₂,研究了其添加对MgH₂储氢性能的影响。结果发现,固溶体MAX相(Ti_0.5V_0.5)₃AlC₂中的Ti和V元素通过协同作用,呈现出更高的催化活性。添加质量分数10%(Ti_0.5V_0.5)₃AlC₂的MgH₂样品的起始放氢温度为230℃,较原始MgH₂降低了60℃。在275℃下等温放氢,(Ti_0.5V_0.5)₃AlC₂添加样品的放氢速率可达0.35%·min^-1,是原始MgH₂样品的4倍左右。此外,完全放氢后的MgH₂-10%(Ti_0.5V_0.5)₃AlC₂样品在150℃、5 MPa氢压下,可在60 s内吸收4.7%的氢。计算显示,MgH₂-10%(Ti_0.5V_0.5)₃AlC₂样品的表观活化能为79.6 kJ·mol^-1,较原始MgH₂(153.8 kJ·mol^-1)降低了48%,这是MgH₂放氢性能得到改善的主要原因。更多还原

【Abstract】 A solid-solution MAX phase(Ti_0.5V_0.5)₃AlC₂ was successfully synthesized with a pressureless sintering method, and its catalytic effect on hydrogen storage reaction of MgH₂ was systematically investigated. The solid solution MAX phase(Ti_0.5V_0.5)₃AlC₂ exhibited superior catalytic activity, thanks to the synergistic catalysis effect of Ti and V. The on-set dehydrogenation temperature of MgH₂-10%(Ti_0.5V_0.5)₃AlC₂ samples was only 230 ℃(mass fraction of(Ti_0.5V_0.5)₃AlC₂ was 10%), which was 60 ℃ lower than that of pristine MgH₂. The desorption rate of MgH₂-10%(Ti_0.5V_0.5)₃AlC₂ sample at 217 ℃ was calculated to be 0.35%·min^-1, which was 4 times faster than that of the pristine sample. At 150 ℃, the dehydrogenated MgH₂-10%(Ti_0.5V_0.5)₃AlC₂ sample absorbs 4.7% of H₂ within60 s under 5 MPa H₂. The apparent activation energy of the MgH₂-10%(Ti_0.5V_0.5)₃AlC₂ sample was determined to be 79.6 kJ·mol^-1, representing a 48% reduction in the reaction barrier, compared with pristine MgH₂(153.8 kJ·mol^-1). This reasonably explains the significant improvement in dehydrogenation performance.更多还原