分子动力学模拟不同类型MOFs材料对NO2气体扩散影响  

Molecular Dynamic Simulation on Effects of MOFs Type on NO_2 Diffusivity

作　　者：余园园 杨犁[1] 彭昌军[2] 孙炜[1] YU Yuan-yuan;YANG Li;PENG Chang-jun;SUN Wei(Key Laboratory of Green Chemical Process of Ministry of Education,Key Laboratory of Novel Reactor and Green Chemical Technology of Hubei Province,School of Chemical Engineering and Pharmacy,Wuhan Institute of Technology,Wuhan 430205,China;School of Chemistry and Molecular Engineering,East China University of Science and Technology,Shanghai 200237,China)

机构地区：[1]武汉工程大学绿色化工过程教育部重点实验室,湖北省新型反应器与绿色化学工艺重点实验室,化工与制药学院,湖北武汉430205 [2]华东理工大学化学与分子工程学院,上海200237

出　　处：《高校化学工程学报》2018年第4期823-830,共8页Journal of Chemical Engineering of Chinese Universities

基　　金：国家自然科学基金(21406172); 湖北省自然科学基金(2016CFB388)

摘　　要：利用分子动力学模拟考察了不同浓度条件下NO_2气体在金属有机骨架材料(MOFs)中的自扩散速率,并讨论了气体自扩散速率与材料结构之间的关系。研究结果表明NO_2气体在IRMOF系列材料、具有开放金属位点的MOFs材料和ZIF系列材料中的自扩散系数随着气体浓度增加先升高后降低;在MIL系列材料中的自扩散系数仅随着气体浓度增加而降低。其扩散性能主要受材料最小孔径和孔隙率影响,在同系列材料中最小孔径和孔隙率越大,NO_2气体的自扩散系数越大。其中NO_2气体在IRMOF-9、Mg MOF-74、ZIF-3、MIL-47和MIL-53Crht等材料中均具有较好扩散性能。通过气体分子在材料中的径向分布函数图、模拟轨迹等探讨了气体在MOFs材料中的扩散机理。研究发现MOFs材料金属簇吸附性能的强弱影响NO_2气体随浓度变化的自扩散系数曲线。同时研究了无限稀释条件下NO_2气体在MOFs材料中的自扩散系数D(0),从而获得NO_2在MOFs材料中的活化能。NO2 self-diffusivity in metal-organic frameworks（MOFs） was studied via molecular dynamics（MD） simulation under different molecular concentrations, and effects of material geometry was analyzed. The results show that NO2 self-diffusivity increases first and then decreases with the increase of NO2 concentration in IRMOF, open-metal sites and ZIF MOFs, and it decreases linearly with the increase of NO2 concentration in MIL MOFs. The self-diffusivity behaviors are mainly affected by pore limiting diameter and void fraction of MOFs. Higher self-diffusivities of NO2 were obtained in MOFs with larger pore limiting diameters and void fractions. IRMOF-9, Mg MOF-74, ZIF-3, MIL-47 and MIL-53 Crht showed good diffusion performance of NO2 gas. Diffusion mechanism was studied by radial distribution functions and MD trajectory of NO2 gas in MOFs. The results show that self-diffusion coefficients of NO2 gas are affected by the interaction of metal cluster of MOFs and NO2 molecule. Activation energies of NO2 in MOFs are obtained through fitting simulated self-diffusivities at infinite dilution D（0） at various temperatures using Arrhenius equation.

关 键 词：分子动力学模拟 自扩散系数 MOFs材料 NO2 

分 类 号：O552.2[理学—热学与物质分子运动论]