乙炔等离子体合成纳米Mg颗粒及贮氢性能研究

Research on Hydrogen Storage Behavior of Mg Nanoparticles Synthesized by Acetylene Plasma

摘要: 通过在等离子体蒸发金属Mg的过程中引入乙炔气体，制备了纳米Mg颗粒并进行了贮氢性能研究。结果表明，随着乙炔浓度的提高，制备出的纳米Mg颗粒的尺寸有减小的趋势，但乙炔浓度超过21.7%摩尔浓度时，制备出的纳米Mg颗粒的尺寸不再减小，当乙炔的摩尔浓度为21.7%时，纳米Mg颗粒尺寸为40 nm左右，其比表面积为27.1 m²∙g⁻¹。在473 K，4 MPa氢气压力下1小时可吸氢接近饱和。其吸氢活化能为61.6 kJ∙mol⁻¹ H₂，放氢活化能为114 kJ∙mol⁻¹ H₂，其吸放氢反应焓为ΔH = −65.5 kJ∙mol⁻¹ H₂，反应熵为ΔS = −122.7 J∙K⁻¹∙mol−1 (H₂)，且在623 K, 4 MPa H₂及30次吸放氢循环下，其吸氢容量没有衰减。

Abstract: Acetylene gas was introduced in Mg metal plasma evaporization for Mg nanoparticles manufacture, and hydrogen storage behavior of Mg nanoparticles was systematically investigated. The results show that Mg nanoparticles’ size decreased with the increase of acetylene concentration. Mg nanoparticles’ size stopped decrease when acetylene concentration exceeded 21.7% molar con-centration. Mg nanoparticles’ size was about 40 nm and specific area was about 27.1 m²∙g⁻¹ when acetylene concentration was 21.7% molar concentration. Hydrogen absorption process could ap-proaching saturation in 1 hour under 4 MPa hydrogen gas at 473 K. Hydrogen absorption activation energy was 61.6 kJ∙mol⁻¹ H₂, and hydrogen desorption activation energy was 114 kJ∙mol⁻¹ H₂. Hydrogen absorption reaction enthalpy ΔH = −65.5 kJ∙mol⁻¹ H₂, and hydrogen absorption reaction entropy ΔS = −122.7 J∙K⁻¹∙mol−1 (H₂). Hydrogen absorption capability wasn’t attenuate after 30 times hydrogen absorption/desorption circulation in 4 MPa H₂ at 623 K.