Effect of Water on CO2 Capture by Aprotic Heterocyclic Anion (AHA) Ionic Liquids
Effect of Water on CO2 Capture by Aprotic Heterocyclic Anion (AHA) Ionic Liquids
复制标题
DOI：
10.1021/acssuschemeng.9b04424
复制
发表时间：
2019-10-07
影响因子：
8.4
通讯作者：
Brennecke, Joan F.
中科院分区：
文献类型：
--
作者：
Bonilla, Gabriela M. Avelar;Morales-Collazo, Oscar;Brennecke, Joan F.
研究了三种非质子杂环阴离子（AHA）离子液体（三乙基（辛基）膦2-氰基吡咯烷[P-2228]-[2CNPyr]、三乙基膦苯并咪唑[P-2222] [BnIm]和三乙基（辛基）膦吲唑[P-2228][Inda]）在水存在下与CO2的反应。我们提出了一种反应机理，其中除了阴离子与CO反应以形成氨基甲酸酯之外，阴离子与水反应（即，水的自然离解或碳酸的形成导致水中的水合氢离子）并被还原，留下CO2与氢氧化物反应形成碳酸氢盐。[P-2228][2CNPyr]和[P-2222] [BnIm]的这种机理通过用于鉴定和定量反应产物的H-1 NMR、C-13 NMR、杂原子单量子相关NMR和杂原子多键相关NMR来证实。然而，与其他两种离子液体不同，[P-2228] [Inda]仅与水接触时表现出阴离子的再质子化;即，不需要CO来形成碳酸以增加水中的质子浓度。通过使用容量法在水存在下测量CO2在[P-2228][2CNPyr]和[P-2222][BnIm]中的溶解度几个循环来测试再质子化反应的可逆性。以前，我们已经表明，AHA离子液体与CO2形成氨基甲酸酯（在没有水的情况下）的反应是可逆的。此外，在水存在下对包封的[P-2228][2CNPyr]和[P-2222][BnIm]进行CO2溶解度再循环性测试。AHA离子液体和CO2在水存在下的两种反应似乎是完全可逆的。包封的离子液体在水的存在下表现出良好的CO2捕获能力和良好的可回收性结果，以及。
The reaction between three aprotic heterocyclic anion (AHA) ionic liquids (ILs) (triethyl(octyl)phosphonium 2-cyanopyrrolide [P-2228]-[2CNPyr], triethylphosphonium benzimidazolide [P-2222] [BnIm], and triethyl(octyl)phosphonium indazolide [P-2228][Inda]) and CO2, in the presence of water, is investigated in this study. We propose a reaction mechanism where, in addition to the reaction of the anion with CO, to form carbamate, the anion reacts with water (i.e., hydronium ions in water from either the natural dissociation of water or the formation of carbonic acid) and is reprotonated, leaving CO2 to react with hydroxide to form bicarbonate. This mechanism is confirmed for [P-2228][2CNPyr] and [P-2222] [BnIm] by H-1 NMR, C-13 NMR, heteronuclear single quantum correlation NMR, and heteronuclear multiple bond correlation NMR, which were used to identify and quantify the reaction products. However, unlike the other two ILs, [P-2228] [Inda] exhibits reprotonation of the anion when in contact with water only; i.e., CO, is not needed to form carbonic acid to increase the proton concentration in water. The reversibility of the reprotonation reaction was tested by measuring the CO2 solubility in [P-2228][2CNPyr] and [P-2222][BnIm] in the presence of water for several cycles using a volumetric method. Previously, we have shown that the reaction of AHA ILs with CO2 to form carbamate (in the absence of water) is reversible. Additionally, encapsulated [P-2228][2CNPyr] and [P-2222][BnIm] were subjected to a CO2 solubility recyclability test in the presence of water. Both reactions between AHA ILs and CO2 in the presence of water appear to be fully reversible. The encapsulated ILs showed good CO2 capture capacity in the presence of water and good recyclability results, as well.