新型阴离子功能化多位点离子液体的设计合成及其调控SO2捕集行为的研究

Large sulfur released into the atmosphere as SO2 during the burning of fossil fuels. Control and minimize the emissions of SO2 is highly sought, as it is harmful to the environment and human health. Ionic liquids (ILs) have been proposed as better absorbents for SO2 capture due to their outstanding properties, like extremely low vapor pressure, wide liquid temperature range, non-flammability, and tunable property. Recently, the chemisorption has high capacity for gas absorption along with high absorption enthalpy, which results in difficult desorption as well as high energy demand for regeneration. Until now, development of alternative ILs for further improving SO2 capture that are able to achieve both enhanced capacity and improved desorption are always highly sought. This situation inspires us to develop a new method for efficient SO2 capture in order to reach capacity-increasing and energy-saving. In this work, we want to develop a new method to enhance the SO2 absorption capacity as well as reducing the enthalpy. Several kinds of anion-functionalized multiple-site based ILs were designed and would be synthesized. The effects of functional group number, different central atom, and the structure of functional group on the SO2 capture would be investigated through multiple-site interaction under different temperatures and pressures. The effects of water, CO2 on the selectivity of SO2 capture were also would be studied. Through a combination of absorption experiment, spectroscopic investigation, and quantum chemical calculation, we would show that both enhanced capacity and reduced enthalpy for the capture of SO2 could be achieved due to the dual role of functional group both as an added interaction site and as an electron-withdrawing group, resulting in highly efficient and excellent reversible process for SO2 capture. It provides a novel method for the design of multiple-site based ionic liquids and industrial application of ionic liquids.

煤燃烧所释放的SO2，严重污染环境并对人类健康造成重大威胁，从而引起全球的广泛关注。离子液体由于蒸汽压低、稳定性高、液程宽、可设计性强为SO2捕集提供了契机。本项目拟针对目前离子液体捕集SO2研究中普遍存在的能耗高、不易脱附、低浓度下有效质量捕集量低等问题，设计合成一系列新型阴离子功能化多位点离子液体，使其既可以通过增加作用位点提高捕集量，又可以通过调节阴阳离子间作用力的大小，调变各作用位点的电荷分布，从而调控吸收焓，改善脱附过程。结合吸收实验、谱学方法和量子化学计算，研究官能团数目、中心位点特性和不同官能团结构的阴离子对离子液体的结构和SO2的捕集行为的影响；考察水分、CO2等杂质对SO2捕集的影响；研究捕集SO2的动力学行为。构建新型阴离子功能化多位点离子液体的结构与SO2捕集量、吸收焓之间的关系，实现SO2的高选择性、高捕集量、低能耗、循环可逆捕集。

离子液体由于其蒸汽压低、稳定性高、液程宽、可设计性强等优点和特点，为SO2捕集提供了契机。本项目主要针对目前离子液体捕集SO2研究中普遍存在的能耗高、不易脱附、低浓度下有效捕集量低等问题，设计合成了一系列酰胺类、含氟乙酰丙酮类以及含硝基类、卤代羧酸类、取代唑基类、含氰基类、含醛基类阴离子功能化多位点离子液体，通过调节多位点离子液体阴阳离子的分子结构，调变各作用位点的电荷分布，从而调控吸收焓，改善脱附过程，使其既可以通过增加作用位点提高捕集量，又可以通过调节阴阳离子间作用力的大小来改善脱附效果。结合吸收实验、谱学方法、量子化学计算，研究了阴离子结构、官能团数目、碱性、取代基效应等对离子液体的结构和SO2的捕集行为的影响；考察了SO2分压、温度、水分、CO2等杂质对SO2捕集的影响；建立了离子液体的结构、SO2 捕集量、吸收焓、阴离子碱性之间的构效关系；实现了对SO2 的高选择性、高捕集量、低能耗、循环可逆捕集。从而为新型多位点离子液体的分子设计及其在SO2捕集中的工业应用做出一些贡献。