化学学报 ›› 2005, Vol. 63 ›› Issue (6): 484-490. 上一篇    下一篇

研究论文

H2在K0-MWCNTs上储存和吸附/脱附特性研究

武小满,王毅,董昆明,周金梅,林国栋,张鸿斌*   

  1. (厦门大学化学化工学院 固体表面物理化学国家重点实验室 厦门 361005)
  • 收稿日期:2004-04-14 修回日期:2004-11-20 出版日期:2005-03-28 发布日期:2010-12-10
  • 通讯作者: 张鸿斌

Study of Storage and Adsorption/Desorption Characteristics of H2 on MWCNTs Modified by Metal Potassium

WU Xiao-Man, WANG Yi, DONG Kun-Ming, ZHOU Jin-Mei, LIN Guo-Dong, ZHANG Hong-Bin*   

  1. (Institute of Chemistry & Chemical Engineering, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005)
  • Received:2004-04-14 Revised:2004-11-20 Online:2005-03-28 Published:2010-12-10
  • Contact: ZHANG Hong-Bin

利用高压容积法辅以卸压升温脱附排水法, 测定金属K修饰多壁碳纳米管对H2的吸附储存容量. 结果表明, 在室温(25 ℃), 7.25 MPa实验条件下, x%K0-MWCNTs (x%=30%~35%, 质量百分数)对H2的吸附储存容量可达3.80 wt%(质量百分数), 是相同条件下单纯MWCNTs氢吸附储量的2.5倍; 室温下卸至常压的脱附氢量为3.36 wt%(占总吸附氢量的~88%), 后续升温至673 K的脱附氢量为0.41 wt%(占总吸附氢量的~11%). 利用LRS和H2-TPD-GC/MS等谱学方法对H2/K0-MWCNTs吸附体系的表征研究表明, H2在K0-MWCNTs上吸附存在非解离 (即分子态)和解离(即原子态)两种吸附态; 在≤723 K温度下, H2/K0-MWCNTs体系的脱附产物几乎全为H2气; 723 K以上高温脱附产物不仅含H2, 也含有CH4, C2H4和C2H2等C1/C2-烃.

关键词: MWCNTs, K0-MWCNTs, H2的吸附储存, H2/K0-MWCNTs的Raman光谱

Storage capacity of H2 in a kind of potassium-modified multiwalled carbon nanotubes, K0-MWCNTs, was measured by using high-pressure volumetric method combined with desorption water- displacement method. It was experimentally shown that appropriate incorporation of a certain amount of metallic potassium into the MWCNTs could significantly increase the storage capacity of hydrogen. Under conditions of 7.25 MPa and ambient temperature, H2 uptake of 3.8 wt% could be achieved by the x%K0-MWCNTs (x%=30%~35%, mass percentage), which was 2.5 times as high as that by the K0-free MWCNTs under the same conditions. It was also indicated that adsorption of 99% of the H2 was reversible, and that 88% of the stored hydrogen (equalling storage capacities of 3.36 wt%) could be desorbed while the pressure was relieved to atmospheric pressure and ~11% of the stored hydrogen (equalling storage capacities of 0.41 wt%) was desorbed in the following process of elevating temperature from room temperature to 673 K. The Raman-spectroscopic and TPD-MS/GC investigations of the H2/K0-MWCNTs adsorption systems showed that adsorption of H2 on the MWCNTs could occur in associative and dissociative forms, with the observed νs(C—H) for CH2, ν(C—H) for CH and ν(H—H) for H2 (a) at 2856, 3228 and 3946 cm-1, respectively, and that H2 was the predominant products desorbed at temperatures lower than 723 K, whereas in addition to H2, light hydrocarbons such as CH4, C2H4, C2H2, etc. were also involved in the products desorbed at temperatures higher than 723 K.

Key words: MWCNTs, K0-MWCNTs, hydrogen-storage, Raman spectra of H2/K0-MWCNTs