预测型热力学模型及其在混合离子液体吸收天然气中CO2过程的应用

As potential absorbents, ionic liquids have been studied extensively in CO2 removal from natural gas. High solubility and selectivity of the ionic liquids are the keys to improve the gas separation performance, but the pure ionic liquid cannot satisfy the demands. In this project, mixed ionic liquids are used as separation agents to improve the gas separation based on the synergistic effect, and the optimized predictive thermodynamic model is applied in CO2 absorption from natural gas with mixed ionic liquids. Firstly, the suitable mixed ionic liquids will be screened thoroughly by the optimized COSMO-RS model, and the interaction between the suitable mixed ionic liquids will be studied to investigate the synergistic effect. Secondly, the effect of structure and ratio of mixed ionic liquids, temperature and pressure on gas absorption (solubility of CO2/CH4) and gas separation (selectivity of CO2-CH4) will be investigated. In order to describe the thermodynamic phase equilibrium for mixed ionic liquid systems, the predictive UNIFAC model will be established. Finally, the equilibrium stage mathematical model for the mixed ionic liquid absorption and desorption processes is obtained to design and optimize the continuous process of gas separation. This project can provide theoretical foundation for CO2 absorption from natural gas efficiently with mixed ionic liquids.

离子液体作为一种有潜力的吸收剂在脱除天然气中CO2方面得到了广泛关注，选择高溶解度和高选择性的离子液体是提高气体分离性能的关键，而单一离子液体难以同时满足高溶解度和高选择性的要求。利用两种离子液体的协同机制，本项目拟采用混合离子液体为分离剂提高气体分离性能，提出将优化的预测型热力学模型应用于混合离子液体吸收天然气中CO2过程的新思路。通过改进和优化COSMO-RS模型的可调参数，筛选出合适的混合离子液体吸收剂，并阐明其协同机制，探索混合离子液体结构、配比、吸收温度和压力等对气体吸收（CO2/CH4溶解度）和气体混合物分离性能（CO2-CH4选择性）的影响规律，建立混合离子液体体系的UNIFAC预测型热力学模型来描述其相平衡，进而建立混合离子液体吸收-解吸过程的平衡级数学模型，对吸收-解吸工艺流程进行设计和优化。项目的实施将为混合离子液体高效吸收天然气中CO2提供理论依据。

离子液体作为一种有潜力的吸收剂在脱除天然气中CO2方面得到了广泛关注，选择高溶解度和高选择性的离子液体是提高气体分离性能的关键，而单一离子液体难以同时满足高溶解度和高选择性的要求。利用两种离子液体的协同机制，本项目提出以混合离子液体为分离剂提高气体分离性能的新思路，并将预测型热力学模型应用在混合离子液体吸收天然气中CO2过程。通过改进和优化COSMO-RS模型，建立了筛选出合适的混合离子液体吸收剂的方法，揭示离子液体阴、阳离子结构对CH4/CO2混合物分离性能的影响规律、建立适用的混合离子液体热力学模型、从分子水平上分析混合离子液体脱除天然气中CO2的作用机理，并对混合离子液体吸收CO2的过程进行模拟和优化，结合参变性能分析结果，确定了主要设计和操作参数。研究结果对混合离子液体用于其他气体混合物的分离过程具有一定的参考价值。