物理化学学报 >> 2005, Vol. 21 >> Issue (10): 1138-1142.doi: 10.3866/PKU.WHXB20051015

研究论文 上一篇    下一篇

分子模拟研究气体在室温离子液体中的溶解度

吴晓萍; 刘志平; 汪文川   

  1. 北京化工大学化学工程学院分子与材料模拟研究室, 教育部纳米材料重点实验室, 北京 100029
  • 收稿日期:2005-03-04 修回日期:2005-05-27 发布日期:2005-10-15
  • 通讯作者: 刘志平 E-mail:liuzhp@mail.buct.edu.cn

Molecular Dynamics Simulation of Gas Solubility in Room Temperature Ionic Liquids

WU Xiao-ping; LIU Zhi-ping; WANG Wen-chuan   

  1. Division of Molecular and Materials Simulation, Key Laboratory of Nanomaterials, Ministry of Education, Institute of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029
  • Received:2005-03-04 Revised:2005-05-27 Published:2005-10-15
  • Contact: LIU Zhi-ping E-mail:liuzhp@mail.buct.edu.cn

摘要: 在作者先前建立的分子力场基础上, 采用Widom粒子插入法预测了CO2、N2、O2、Ar及CH4等5种气体在多种咪唑类离子液体中的溶解度, 包括2种侧链长度的阳离子和3种阴离子. 首先考察了256个离子对组成的体系中溶质分子插入次数对计算结果的影响, 在此基础上计算了不同温度下气体在1-丁基-3-甲基咪唑的四氟化硼盐([bmim][BF4])和六氟化磷盐([bmim][PF6])中的溶解度. 计算结果正确反映了CO2气体溶解度的变化趋势, 在[bmim][BF4]中溶解度的模拟结果与实验值符合很好, 且明显优于Pádua等的模拟结果;在[bmim][PF6]中的溶解度较实验值偏高, 精度与文献模拟结果相当;并预测了较高温度下CO2气体在[bmim][BF4]和[bmim][PF6]中的溶解度. 计算结果也正确地反映了5种气体在[bmim][PF6]中溶解度实验值的相对大小. 另外考察了常温下几种气体在不同室温离子液体中的溶解度, 模拟结果表明气体在含有较长碳链和双-三氟甲基磺酰胺阴离子(Tf2N)的离子液体中溶解度较大.

关键词: 室温离子液体, 分子动力学模拟, 粒子插入法, 气体溶解度

Abstract: The solubilities of five gases, CO2, N2, O2, Ar and CH4, in room temperature ionic liquids were studied by Widom test-particle insertion method. A number of 200000 insertions of the solute was decided. The solubility of CO2 in 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) obtained in this work is superior to that of Pádua et al. As for CO2 in 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), the result in this work is similar to previous studies. Furthermore, the solubilities of CO2 in [bmim][BF4] and [bmim][PF6] at high temperatures were predicted. The experimental relative solubility order for the 5 gases in [bmim][PF6] is reproduced by simulation. In addition, the solubility of 5 gases in different ionic liquids shows that it is bigger in ionic liquids with long alkyl chain or with bis((trifluoromethyl)sulfonyl) amide anion than in [bmim][BF4].

Key words: Room temperature ionic liquid, Molecular dynamics simulation, Test- particle insertion method, Gas solubility