Abstract:

In observation of developing new kinds of adsorbent for the storage of natural gas by adsorption, comparison of adsorption equilibrium of methane was made between the graphene sheets and the activated carbon.The graphene sheets and the activated carbon, which respectively has a specific surface area about 300 and 2074 m²·g^-1, were selected and performed adsorption equilibrium tests of methane within temperature-pressure range respectively about 273-293 K and 0-8 MPa.A lattice theory based adsorption model and 10-4-3 interaction potential function were employed to determine the maximum surface concentration and the interaction potential from the adsorbent as well as among the adsorbate molecules within the adsorption layer.It shows that the interaction energy among methane molecules confined within the adsorbed layer upon the surface of the graphene sheets was larger than that upon the activated carbon.Conclusions are drawn that a more compact state of adsorbed methane molecules can be obtained where the graphene sheets is used, and the graphene sheets having a higher specific surface area could be a promising medium for natural gas storage.

Key words: methane, adsorption, graphene sheets, activated carbon, intermolecular interaction energy

摘要：

以研制新型吸附式天然气(ANG)吸附剂为目的,比较了甲烷在石墨烯和活性炭上的吸附平衡。首先,在温度区间273~293 K、压力范围0~8 MPa,测试甲烷在比表面积分别为300和2074 m²·g^-1石墨烯和活性炭上的吸附平衡数据。其次,应用格子理论导出的通用吸附等温方程,通过吸附平衡态能量分析及10-4-3相互作用势函数求解,确定甲烷分子在石墨烯平面和活性炭上的最大面密度、受到的壁面吸附作用势及其在吸附层内的作用能。结果表明,在相同温度下,吸附甲烷分子在石墨烯上吸附层内的相互作用能较其在活性炭上的大,甲烷分子在石墨烯平面上的集聚更为密集。提高石墨烯的比表面积将有效提高甲烷在其上的吸附容量。

关键词: 甲烷, 吸附, 石墨烯, 活性炭, 分子间作用能