Department of Chemistry, University of Science & Technology of China, Hefei, China.
Phys Chem Chem Phys. 2012 Apr 7;14(13):4589-96. doi: 10.1039/c2cp23642g. Epub 2012 Feb 23.
Efficient technologies/processes for CO(2) capture are greatly desired, and ionic liquids are recognized as promising materials for this purpose. However, the mechanisms for selectively capturing CO(2) by ionic liquids are unclear. In this study, the interactions between CO(2) and 1-n-amino-alkyl-3-methyl-imidazolium tetrafluoroborate, an amino imidazolium ionic liquid (AIIL), in its CO(2) capturing process, are elucidated with both quantum chemistry and molecular dynamics approaches on the molecular level. The effects of the straight aminoalkyl chain length in imidazolium-based cations on CO(2) capture are explored, and thereby the factors governing CO(2) capture for this ionic liquid family, e.g., ionic liquid structure, charge distribution, intermolecular interactions, thermodynamic properties and absorption kinetics, are analyzed. Molecular dynamics simulations are used to study the diffusion of the involved compounds and liquid structures of the CO(2)-AIIL systems. The results show that the amino-alkyl chain length plays an important role in governing the absorption properties of AIILs, including the free energies of absorption, equilibrium constants, desorption temperature, absorption rate constants, diffusion coefficients, and organization of CO(2) around cations and anions. This study provides useful information about rational design of ionic liquids for efficient CO(2) capture.
高效的 CO2 捕获技术/工艺备受期待，离子液体被认为是实现这一目标的有前途的材料。然而，离子液体选择性捕获 CO2 的机制尚不清楚。在这项研究中，我们通过量子化学和分子动力学方法在分子水平上阐明了 CO2 与 1-氨基-烷基-3-甲基-咪唑𬭩四氟硼酸盐（氨基咪唑离子液体（AIIL））在其 CO2 捕获过程中的相互作用。研究了咪唑阳离子中直链氨基烷基长度对 CO2 捕获的影响，从而分析了这种离子液体家族中 CO2 捕获的控制因素，例如离子液体结构、电荷分布、分子间相互作用、热力学性质和吸收动力学。分子动力学模拟用于研究所涉及化合物的扩散和 CO2-AIIL 体系的液体结构。结果表明，氨基-烷基链长在控制 AIIL 的吸收性质方面起着重要作用，包括吸收自由能、平衡常数、解吸温度、吸收速率常数、扩散系数以及 CO2 在阳离子和阴离子周围的组织。这项研究为设计高效 CO2 捕获的离子液体提供了有用的信息。
