高等学校化学学报 ›› 2016, Vol. 37 ›› Issue (9): 1660.doi: 10.7503/cjcu20160337

• 物理化学 • 上一篇    下一篇

1-乙胺基-3-甲基咪唑四氟硼酸盐吸收CO2的理论研究

张慧1,2(), 张红梅1, 王连军1, 沈锦优1   

  1. 1. 南京理工大学环境与生物工程学院, 南京 210094
    2. 南京信息工程大学江苏省大气环境与装备技术协同创新中心, 南京 210044
  • 收稿日期:2016-05-12 出版日期:2016-09-10 发布日期:2016-08-26
  • 作者简介:联系人简介: 张 慧, 女, 讲师, 主要从事大气污染控制新技术及新材料的开发与研究. E-mail:zhanghui13401@163.com
  • 基金资助:
    江苏省高校自然科学研究项目(批准号: 12KJB610003)资助

Density Functional Theory Studies on the CO2 Absorption by 1-Ethylamine-3-methylimidazolium Tetrafluoroborate

ZHANG Hui1,2,*(), ZHANG Hongmei1, WANG Lianjun1, SHEN Jinyou1   

  1. 1. School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
    2. Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology(CICAEET),Nanjing University of Information Science & Technology, Nanjing 210044, China
  • Received:2016-05-12 Online:2016-09-10 Published:2016-08-26
  • Contact: ZHANG Hui E-mail:zhanghui13401@163.com
  • Supported by:
    † Supported by the Natural Science Research Project of Colleges and Universities in Jiangsu Province, China(No.12KJB610003).

摘要:

采用密度泛函理论(DFT)对离子液体1-乙胺基-3-甲基咪唑四氟硼酸盐([NH2e-mim][BF4])吸收CO2的反应机理进行了研究. 在B3LYP/6-311++G(d,p)计算水平下, 对离子液体[NH2e-mim][BF4]的结构及与CO2反应的中间体、 过渡态和产物进行了全优化, 获得了优化结构的构型参数、 振动频率和热力学数据. 利用自然键轨道(NBO)分析了离子液体[NH2e-mim][BF4]和CO2的自然电荷布居. 计算结果表明, 通过阳离子[NH2e-mim]+自偶解离产生的阳离子[NH3e-mim]2+能与阴离子[BF4]-结合形成更强的离子键. 根据反应吉布斯自由能变(ΔG 0—)和焓变(ΔH 0—)的计算结果, 判断离子液体[NH2e-mim][BF4]吸收CO2按理论摩尔比2:1分步进行反应, 吸收过程中质子的转移需克服52.51 kJ/mol的能垒.

关键词: 离子液体, 二氧化碳, 密度泛函理论, 吸收机理

Abstract:

CO2 absorption mechanism by ionic liquids 1-ethylamine-3-methylimidazolium tetrafluoroborate, which was formulated as [NH2e-mim][BF4], was described via density functional theory(DFT). The structure of ionic liquids [NH2e-mim][BF4], their reaction intermediates, transition states and products, were optimized using the B3LYP/6-311++G(d, p) basis method, with the optimized configuration parameters, vibration frequencies and thermodynamics data obtained. Furthermore, the natural bond orbital atomic charge assignments were also calculated via the natural bond orbital(NBO) method. The computational results demonstrated that the divalent cation [NH3e-mim]2+, which was produced by the autoprotolysis of cation [NH2e-mim]+, could be easily combined with anion [BF4]-, with stronger ionic bond formed. According to the calculation results of standard Gibbs free energy(ΔG 0—) and enthalpy(ΔH 0—), it could be inferred that the absorption of CO2 onto ionic liquids [NH2e-mim][BF4] was step by step, in accordance with the theoretical molar ratio of 2:1. During the absorption process, the energy barrier of 52.51 kJ/mol should be overcome for proton transfer reaction.

Key words: Ionic liquid, CO2, Density functional theory(DFT), Absorption mechanism

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