化工进展 ›› 2023, Vol. 42 ›› Issue (11): 6015-6030.DOI: 10.16085/j.issn.1000-6613.2022-2319

• 资源与环境化工 • 上一篇    

多元胺-TFSA型质子化离子液体吸收CO2的理论分析

米泽豪1(), 花儿1,2,3()   

  1. 1.北方民族大学化学与化学工程学院,银川 宁夏 750021
    2.国家民委化工技术基础重点实验室
    1.宁夏 银川 750021,宁夏太阳能化学转化技术重点实验室,宁夏 银川 750021
  • 收稿日期:2022-12-15 修回日期:2023-03-07 出版日期:2023-11-20 发布日期:2023-12-15
  • 通讯作者: 花儿
  • 作者简介:米泽豪(1998—),男,硕士研究生,研究方向为离子液体。E-mail:875501689@qq.com
  • 基金资助:
    宁夏高等学校研究项目(NGY2020063)

Theoretical analysis of CO2 absorption by polyamines-TFSA type protic ionic liquids

MI Zehao1(), HUA Er1,2,3()   

  1. 1.Chemical Science and Engineering College, North Minzu University, Yinchuan 750021, Ningxia, China
    2.Key Laboratory of Chemical Engineering and Technology, State Ethnic Affairs Commission, Yinchuan 750021, Ningxia, China
    3.Ningxia Key Labaratory of Solar Chemical Conversion Technology, Yinchuan 750021, Ningxia, China
  • Received:2022-12-15 Revised:2023-03-07 Online:2023-11-20 Published:2023-12-15
  • Contact: HUA Er

摘要:

开展了以质子化的正己胺(HHexam)、己基乙二胺(HHexen)及己基二亚乙基三胺(HHexdien)为阳离子的TFSA [== (CF3SO2)2N-]型质子化离子液体(PILs),即[HHexam][TFSA]、[HHexen][TFSA]及[HHexdien][TFSA]型PILs吸收CO2的研究。首先,选择密度泛函理论,在M06-2X/6-311G(d, p)水平下,对上述3种PILs的构型进行优化,分别得到了其较稳定构象,结果显示,PILs的阳离子中N—H和阴离子中N原子间主要形成N—H···N型较强氢键。然后,分别利用其中最稳定构象,创建并优化PILs-nCO2构型,PILs和nCO2分子间主要形成N—H···O型弱或中等强度氢键。主要氢键部位N—H···O中N—H键的振动频率的变化值、电子密度值及二阶微扰能的计算结果显示,[HHexam][TFSA]、[HHexen][TFSA]及[HHexdien][TFSA]分别与2、3、4分子CO2结合时将不再形成氢键网络。采用COSMOtherm软件计算的CO2在3种PILs中的亨利常数(kPa)大小为[HHexam][TFSA] (1.91×104) > [HHexen][TFSA] (1.68×104) > [HHexdien][TFSA] (1.51×104),即3种PILs对CO2的溶解能力大小为极性头部具有3个氨基的[HHexdien][TFSA] > 2个氨基的[HHexen][TFSA] > 1个氨基的[HHexam][TFSA]。以上结果中可以看出,PILs结构中氨基数目的多少对其吸收CO2的能力有较显著影响,即随着PILs结构中氨基数目的增多,其对CO2的溶解能力随之增大。

关键词: 多元胺型质子化离子液体, 二氧化碳, 分子间氢键作用, 密度泛函理论, 分子中原子理论

Abstract:

Three protic ionic liquids (PILs) composed of the same anion of [TFSA== (CF3SO2)2N-] and different cations of N-hexylammonium (HHexam+), monoprotic hexylethylenediaminium (HHexen+) and hexyldiethylenetriaminium (HHexdien+), [HHexam][TFSA], [HHexen][TFSA], and [HHexdien][TFSA] were studied for the absorption of CO2. First, the more stable configurations of the three PILs were optimized via the M06-2X/6-311G(d,p) of the density functional theory. The results indicated that the stronger N—H···N-type hydrogen bonds were formed mainly between the N-atoms in the cations and the N-atoms in the anion of the PILs. Then, the configurations of PIL-nCO2 were optimized. The N—H···O-type weak- or moderate-strength hydrogen bonds were formed mainly between the N—H bond in the cation of the PIL and the O atoms of CO2. The results of the vibrational frequency of the N—H bond, and the electron density and the second-order perturbation energy of N—H···O showed that a single molecule of [HHexam][TFSA], [HHexen][TFSA] and [HHexdien][TFSA] was saturated when bonded with 2,3 and 4 CO2 molecules, respectively. Meanwhile, the results calculated by COSMOtherm software found that the Henry constants (kPa) for CO2 in the three PILs varied as 1.91×104 for [HHexam][TFSA]>1.68×104 for [HHexen][TFSA]>1.51×104 for [HHexdien][TFSA], indicating that the solubility of CO2 in the PILs followed the order of [HHexdien][TFSA] with three amino groups in the polar head > [HHexen][TFSA] with two amino groups > [HHexam][TFSA] with one amino group. These results suggested that the number of amino groups in the PIL structure had a significant effect on its ability to absorb CO2. With increasing number of amino groups in the structure of PILs, its solubilization capacity for CO2 increased.

Key words: protic ionic liquids with polyamines, carbon dioxide, intermolecular hydrogen bonding, density functional theory (DFT), atoms in molecules (AIM)

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