多孔金属有机骨架材料储氢性能分子模拟  

Molecular Simulation on Hydrogen Storage Capacities of Porous Metal Organic Frameworks

作　　者：吴选军[1] 郑佶[1] 李江[1] 蔡卫权[1] 

机构地区：[1]武汉理工大学化学工程学院,武汉430070

出　　处：《物理化学学报》2013年第10期2207-2214,共8页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(51142002;51272201);中央高校基本科研业务费专项资金(2012142;2013-II-014)资助项目~~

摘　　要：采用优化的DREIDING力场参数,通过巨正则系综蒙特卡洛(GCMC)模拟方法对H2在IRMOF-1、IRMOF-61和IRMOF-62共3种金属有机骨架(MOFs)材料中的吸附平衡性能进行了比较研究.结果表明,该力场能够在全压力范围内很好地复制H2在IRMOF-62材料中的等温吸附曲线;但对低压下H2在IRMOF-61中的等温吸附曲线预测出现低估.与IRMOF-1相比,具有互穿骨架结构的IRMOF-61和IRMOF-62材料在常温下的储氢能力并无明显提高.进一步比较77 K时100 kPa、3.0 MPa下H2在上述MOFs材料中达到吸附平衡时的几率密度分布发现,H2会优先吸附在Zn4O骨架附近靠近苯环的位置;对具有互穿结构的MOFs材料而言,由于其孔腔尺寸缩小,使得H2优先吸附位区域零散化.适当长度的有机配体形成的互穿骨架结构能增强与H2分子之间的相互作用,具备较高的储氢能力;而有机配体尺寸过长则会增加骨架结构中H2吸附死角,对H2的吸附能力反而出现下降.The adsorption equilibrium properties of H2 molecules in various metal-organic frameworks （MOFs） including IRMOF-61, IRMOF-62, and IRMOF-1 were studied using the grand canonical Monte Carlo （GCMC） simulation method with the optimized parameters obtained using the DREIDING force field. The calculated parameters could exactly reproduce the adsorption isotherms of H2 molecules in IRMOF-62. However, they may underestimate the adsorption isotherm of H2 molecules in IRMOF-61 at low pressure. The H2 storage capacities of IRMOF-61 and IRMOF-62 with interpenetrating frameworks were not significantly higher than that of IRMOF- 1 at room temperature. H2 molecules were preferentially adsorbed near Zn,O units, which were located close to the benzene rings, according to the probability density distribution of H2 molecules in the above MOFs under adsorption equilibrium conditions at 77 K, 100 kPa, and 3.0 MPa. For the MOFs with interpenetrating frameworks, the area with preferential adsorption sites for H2 molecules is smaller and more scattered than the MOF without because of their smaller cavity sizes. The organic linker should be of appropriate length to promote the formation of an interpenetrating framework, which can enhance the interaction between the framework and H2 molecules, and thus improve H2 storage capacity. If the organic linker is too long, it will decrease the adsorption capacity of the MOF for H2 because more corners unable to adsorb H2 are formed.

关 键 词：金属有机骨架材料 多孔材料 巨正则系综蒙特卡洛模拟 储氢 等温吸附 

分 类 号：O641[理学—物理化学]