受限离子液体中气体溶解度的分子热力学研究

Study of the gas solubility in confined ionic liquids (ILs) (e.g. immobilized ILs) is the key to overcome the bottleneck in the application of ILs for acid gas separation. Considering the huge number of ILs that can be synthesized, the pure experimental methodology is impractical; due to the complexity of the studied system, theoretical study is still limited. This project aims at developing a predictive model to study the structural and thermodynamic properties of the IL-containing systems related to gas separation on the basis of our previous work on theoretical modeling of confined simple fluid; meanwhile, based on the natural porous material-palygorskite, the gas separation with palygorskite-immobilized ILs is investigated. Specifically, a new ionic free energy functional is proposed to make PC-SAFT-DFT applicable for confined IL-containing systems, and a new GE mixing rule is developed to improve the model prediction capacity for the strongly asymmetric gas/ILs mixture. Combining the model development and experimental measurements, the contact angle of IL is quantitatively correlated to the palygorskite surface-IL interaction parameter. Furthermore, the effect of palygorskite pore size distribution, surface property, IL and temperature on the solubility and selectivity is systematically investigated, revealing the mechanism on how to adjust the gas separation capacity and selectivity. The results from this project will provide fundamental knowledge in the design of porous material-immobilized ILs and their applications in gas separation technology.

研究受限离子液体（固载离子液体）中气体的溶解性质是解决离子液体在气体分离应用瓶颈问题的关键。离子液体数量巨大，仅依赖实验测定获得受限溶解性质难以满足需求，该体系复杂，导致相关预测模型研究极为缺乏。本项目拟在前期针对受限简单流体的理论模型研究的基础上，建立受限离子液体分离气体体系的结构和热力学性质的预测模型；并且基于天然多孔材料-凹土，研究其固载离子液体分离气体。项目通过提出新的离子项自由能泛函，实现PC-SAFT-DFT模型对受限离子液体体系的应用，同时创新性的建立GE模型混合规则，改进模型对强非对称气体/离子液体的预测能力。通过模型和实验相结合，定量关联离子液体的接触角和壁面-离子液体的相互作用参数。通过系统研究凹土孔径分布、壁面性质、离子液体及温度对气体溶解度、选择性的影响，获得气体分离容量及选择性的调控机制。本研究将为多孔材料固载离子液体的设计及其在气体分离技术的应用提供理论基础。

研究受限离子液体中气体的溶解性质是解决离子液体在气体分离应用瓶颈问题的关键。离子液体数量巨大，仅依赖实验测定获得受限溶解性质难以满足需求，该体系复杂，导致相关预测模型研究极为缺乏。本项目基于本体相PC-SAFT状态方程，提出新的离子项自由能泛函，发展了能应用于受限离子液体体系的PC-SAFT-DFT模型，模型能同时描述含离子液体体系的体相及其在纳米孔道中的受限性质。并将模型应用到典型固体材料受限离子液体分离气体，同时完善模型混合规则，改进模型对强非对称气体/离子液体体系的预测能力。研究揭示了纳米孔道孔径、壁面性质、离子液体种类及压力等对气体溶解度的重要影响，为理解和预测受限离子液体分离气体提供理论依据。此外，我们还系统研究了其它常见离子液体的多种热力学导数性质及粘度，将模型拓展至更多种类的离子液体体系。