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

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。

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 2.96-8.64kJ·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.