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    氢在碳基材料穿插MIL-101(Cr)试样上的吸附平衡

    Adsorption equilibrium of hydrogen on carbon-material incorporated MIL-101(Cr) composites

    • 摘要: 为了实现由碳基材料穿插提高金属有机框架物(MOFs)储氢容量的目的,选择质量分数分别为1%的活性炭和石墨烯穿插MIL-101(Cr)。通过试样的结构表征、微观形貌观察与氢吸附等温线测试,从吸附平衡模型和吸附热两方面来比较其储氢行为。结果表明,在77.15~87.15 K、0~6 MPa,氢在AX-21活性炭穿插(AM-01)和氧化石墨烯(GO)穿插(GM-02)试样上的储氢量比穿插前提高了41.1% 和17.4%;相对于Langmuir方程和Langmuir-Freundlich(L-F)方程,Toth方程的预测精度最高,77.15 K时,Toth方程预测氢在AM-01和GM-02上吸附量的平均相对误差分别为0.55%、0.41%;氢在AM-01和GM-02上的等量吸附热分别为2.96~8.64 kJ⋅mol−1、3.06~8.57 kJ⋅mol−1。由GO或高比表面积的活性炭穿插可增大储氢容量,吸附平衡分析可选用Toth方程。

       

      Abstract: Two typical carbon based materials were employed to incorporate with metal organic frameworks (MOFs) for enhancing hydrogen adsorption performance. 1% activated carbon and graphene sheets were added within the solution for solvo-thermally synthesizing MIL-101(Cr) composites. Adsorption models and isosteric heat of hydrogen adsorption were studied through structural characterization, micromorphology observation and adsorption equilibrium of hydrogen. The results show that there are 41.1% and 17.4% increment of the maximum hydrogen adsorption capacity on sample (AM-01) incorporated with activated carbon AX-21 and GM-02 with graphene oxide (GO), respectively, when comparing those on MIL-101(Cr) under 77.15 -87.15 K and 0-6 MPa. The Toth equation had the highest accuracy when comparing with Langmuir equation and Langmuir-Freundlich equation. The mean relative errors between the experimental data on AM-01 and GM-02, and those predicted by Toth equation were 0.55% and 0.41% at 77.15 K, respectively. The isosteric heat of hydrogen adsorption on AM-01 and GM-02 were 2.96-8.64 kJ⋅mol−1 and 3.06-8.57 kJ⋅mol−1, respectively. These results indicate that adsorption capacity of hydrogen can be increased via incorporation GO or activated carbon with larger specific surface areas, and Toth equation is suitable for analyzing adsorption equilibrium.

       

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