氢在活性炭、石墨烯和金属有机骨架上的吸附平衡

Analysis of the hydrogen adsorption behavior on the typical adsorbing materials

  • 摘要: 为比较不同物理吸附材料的结构参数对其储氢性能的影响,制备和选取了具有超高比表面积的活性炭、石墨烯以及金属有机骨架(MOFs)作为低温吸附储氢的典型材料。首先,利用77 K下氮气在材料上的吸附数据确定了其BET比表面积以及孔径分布的主要结构参数。其次,利用3Flex全自动微孔吸附仪在77-87 K测试了0-0.1 MPa低压下氢在各材料上的吸附量,而后在0.1-8 MPa高压条件下利用PCTPro测试了氢在各材料上的过剩吸附量。最后,分析了各材料的储氢量与其结构参数间的关系。结果表明,在低压下,影响物理吸附材料储氢量的主要因素为孔径分布小于1 nm的微孔;而高压下,氢在多孔材料上的最大过剩吸附量与材料的BET比表面积呈正相关关系,斜率为0.0059 mmol/m2

     

    Abstract: For comparing the effects of the structural properties of adsorbents on the capability for hydrogen storage, three kinds of adsorbents, including activated carbon, graphene sheets (GF) and metal-organic frameworks (MOFs), were synthesized and undertaken adsorption equilibrium tests of hydrogen at temperature of liquid nitrogen. The structural characterization of the prepared samples were firstly conducted employing Micromeritics 3Flex for the adsorption data of nitrogen at 77 K. Then, the adsorption equilibrium tests of hydrogen on those adsorbents had been respectively measured under low pressure of 0-0.1 MPa at temperature of 77-87 K and under high pressure of 0.1-8 MPa at 77 K. Lastly, the relationships of the hydrogen uptake and the structural properties of the adsorbents were analyzed. Results show that the hydrogen uptake of the physical absorbents is mainly affected by the micro-pores with pore size less than 1nm under low pressure, but under high pressure, the maximum amount of excess hydrogen adsorption on the porous material is positively correlated with the BET specific surface area of the material, and the slope is 0.0059 mmol/m2.

     

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