冠醚石墨烷对氦气分离性能的理论研究  

Theoretical study of helium separation performance of crown ether-graphane membranes

作　　者：佟赞 杨银利 徐晶[1] 刘伟[1] 陈亮[2] Tong Zan;Yang Yin-Li;Xu Jing;Liu Wei;Chen Liang(College of Optical,Mechanical and Electrical Engineering,Zhejiang A&F University,Hangzhou 311300,China;School of Physical Science and Technology,Ningbo University,Ningbo 315211,China)

机构地区：[1]浙江农林大学光机电工程学院,杭州311300 [2]宁波大学物理科学与技术学院,宁波315211

出　　处：《物理学报》2023年第6期296-304,共9页Acta Physica Sinica

基　　金：浙江省自然科学基金(批准号:LQ20B030002);国家自然科学基金(批准号:12075211,11975206,11875236,12074341);浙江农林大学科研基金(批准号:2019FR005,2019FR006)资助的课题.

摘　　要：氦气(He)在众多科学和工业领域中都具有非常广泛的应用,He资源的短缺和需求的不断增长使得He分离具有极其重要的意义.石墨烷合成简单、晶体结构稳定,是一种用于构建气体分离膜的潜在理想二维材料.本文通过第一性原理计算,对四种具有不同尺寸冠醚孔的石墨烷膜(crown ether graphane-n,CG-n,n=3,4,5,6)的He分离性能进行了研究.计算结果表明,四种冠醚石墨烷结构都具有较高的热力学、化学稳定性,并且CG-5和CG-6具有合适的孔径,可用于He的有效筛分.在11种气体分子(He,Ne,Ar,H_(2),CO,NO,NO_(2),N_(2),CO_(2),SO_(2)和CH_(4))中,He最容易通过CG-n膜,其能垒分别为4.55,1.05,0.53和0.01 eV.据我们所知,He通过CG-6的能垒是迄今为止报道的最低值,将可显著地提升He的分离效率.基于阿伦尼乌斯方程的选择性计算结果表明,CG-5在较宽的温度范围内(0-600 K)都表现出优异的He选择性(相对于其他10种气体),而CG-6由于冠醚环孔径较大,仅相对于部分气体分子具有较好的He选择性.本研究同时分析了膜孔径大小、气体分子动力学直径和气体分子类型对冠醚石墨烷膜的He分离性能影响的协同机制.因此,孔径合适的冠醚石墨烷膜(CG-5和CG-6)是一类潜在的选择性高、性能优异的He分离膜.Helium(He)is widely used in many scientific and industrial fields,and the shortage of He resources and the growing demand make He separation extremely important.In this work,the He separation performances of a series of graphanes containing crown ether nanopores(crown ether graphane,CG-n,n=3,4,5,6)are studied by first-principles calculations.At first,the minimum energy paths of He and other 10 gas molecules(Ne,Ar,H_(2),CO,NO,NO_(2),N_(2),CO_(2),SO_(2) and CH_(4))passing through CG-n membranes are calculated,and the factors affecting the energy barriers are also investigated.The calculated results show that He is the easiest to pass through all the four CG-n membranes with energy barriers of 4.55,1.05,0.53 and 0.01 eV,respectively.He can be separated by CG-5 and CG-6 with very low energy barriers,and the energy barrier of He passing through CG-6 is the lowest,so far as we know.Moreover,all gas molecules can pass through CG-6 with low energy barriers,including many molecules with large kinetic diameters,such as CO(0.13 eV)and N_(2)(0.16 eV).Therefore,CG-6 is also expected to be used in the screening field of other gas molecules.In addition,it is found that the energy barriers of gas molecules passing through CG-n are synergistically affected by the size of the crown ether nanopore,the kinetic diameter and the type of the gas molecules.Secondly,the diffusion rates of gas molecules passing through CG-5 and CG-6 and the He selectivity towards other 10 gases of CG-5 and CG-6 at different temperatures are calculated.It is found that CG-5 exhibits extremely high He selectivity in a wide temperature range(0-600 K).In summary,the crown ether graphanes CG-5 and CG-6 can serve as excellent He separation membranes with high He selectivity.This work is expected to inspire one to develop other graphene-based two-dimensional separation membranes for separating He and other gas molecules.

关 键 词：冠醚 石墨烷 膜分离 密度泛函理论计算 氦气 

分 类 号：TQ051.893[化学工程] TQ116.41