多元胺-TFSA型质子化离子液体吸收CO_(2)的理论分析  

Theoretical analysis of CO_(2)absorption by polyamines-TFSA type protic ionic liquids

作　　者：米泽豪 花儿 MI Zehao;HUA Er(Chemical Science and Engineering College,North Minzu University,Yinchuan 750021,Ningxia,China;Key Laboratory of Chemical Engineering and Technology,State Ethnic Affairs Commission,Yinchuan 750021,Ningxia,China;Ningxia Key Labaratory of Solar Chemical Conversion Technology,Yinchuan 750021,Ningxia,China)

机构地区：[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,宁夏银川750021 [3]宁夏太阳能化学转化技术重点实验室,宁夏银川750021

出　　处：《化工进展》2023年第11期6015-6030,共16页Chemical Industry and Engineering Progress

基　　金：宁夏高等学校研究项目(NGY2020063)。

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[==(CF_(3)SO_(2))_(2)N^(-)]型质子化离子液体(PILs),即[HHexam][TFSA]、[HHexen][TFSA]及[HHexdien][TFSA]型PILs吸收CO_(2)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-nCO_(2)构型,PILs和nCO_(2)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CO_(2)结合时将不再形成氢键网络。采用COSMOtherm软件计算的CO_(2)在3种PILs中的亨利常数(kPa)大小为[HHexam][TFSA](1.91×10^(4))>[HHexen][TFSA](1.68×10^(4))>[HHexdien][TFSA](1.51×10^(4)),即3种PILs对CO_(2)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CO_(2)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CO_(2)的溶解能力随之增大。Three protic ionic liquids(PILs)composed of the same anion of[TFSA==(CF_(3)SO_(2))_(2)N^(-)]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 CO_(2).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-nCO_(2)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 CO_(2).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 CO_(2)molecules,respectively.Meanwhile,the results calculated by COSMOtherm software found that the Henry constants(kPa)for CO_(2)in the three PILs varied as 1.91×10^(4)for[HHexam][TFSA]>1.68×10^(4)for[HHexen][TFSA]>1.51×10^(4)for[HHexdien][TFSA],indicating that the solubility of CO_(2)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 CO_(2).With increasing number of amino groups in the structure of PILs,its solubilization capacity for CO_(2)increased.

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 

分 类 号：O641.3[理学—物理化学] TQ031[理学—化学]