Cao Lingdi, Huang Junhua, Zhang Xiangping, Zhang Suojiang, Gao Jubao, Zeng Shaojuan
Beijing Key Laboratory of Ionic Liquids Clean Process, State Key Laboratory of Multiphase Complex Systems, Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China.
Phys Chem Chem Phys. 2015 Nov 7;17(41):27306-16. doi: 10.1039/c5cp04050g.
Deep eutectic solvents (DESs) have emerged as promising alternative candidates for CO2 capture in recent years. In this work, several novel DESs were firstly prepared to enhance CO2 absorption. Structural and physical properties of DESs were investigated, as well as their absorption performance of CO2. A distinct depression in the melting point up to 80 K of DESs was observed compared with that of BMIMCl. The observed red shifts of the C2H group in an imidazolium ring and its chemical shifts downfield in NMR spectra are indicative of a hydrogen bond interaction between BMIMCl and MEA. In particular, CO2 uptake in MEA : ILs (4 : 1) at room temperature and atmospheric pressure is up to 21.4 wt%, which is higher than that of 30 wt% MEA (13%). A hydrogen bond related mechanism was proposed in which ILs act as a medium to improve CO2 uptake through hydrogen bonds. Finally, the firstly reported overall heat of CO2 absorption is slightly higher than that of 30 wt% MEA, implying that the hydrogen bonds of DESs contribute to the overall heat of CO2 absorption. This study reveals that the heat of CO2 absorption can be tailored by the proper molar ratio of MEA and ILs.
近年来，深共熔溶剂（DESs）已成为有前景的二氧化碳捕集替代候选物。在本工作中，首先制备了几种新型DESs以增强二氧化碳吸收。研究了DESs的结构和物理性质及其对二氧化碳的吸收性能。与BMIMCl相比，观察到DESs的熔点明显降低高达80 K。咪唑环中C2H基团的红移及其在核磁共振谱中的化学位移向低场移动表明BMIMCl与MEA之间存在氢键相互作用。特别地，在室温及大气压下，MEA与离子液体（ILs）（4∶1）体系对二氧化碳的吸收量高达21.4 wt%，高于30 wt% MEA体系的吸收量（13%）。提出了一种与氢键相关的机制，其中离子液体作为介质通过氢键提高二氧化碳吸收量。最后，首次报道的二氧化碳吸收总热略高于30 wt% MEA体系，这意味着DESs的氢键对二氧化碳吸收总热有贡献。本研究表明，通过MEA和离子液体的适当摩尔比可以调整二氧化碳吸收热。
