离子液体的双Lewis碱性功能设计及硫化氢的高选择性捕获过程研究

The selective capture of hydrogen sulfide (H2S) is one of the most important topics involving energy conservation and emission reduction in the field of energy processing and utilization. The methods currently available for H2S capture in industry usually have some serious problems, such as high energy consumption, low selectivity in separating H2S from carbon dioxide (CO2), and large volatile loss of absorbents to cause environmental pollution. Ionic liquids, as a kind of molten salts with unique properties, have been shown to be candidating absorbents for H2S capture from the research work in recent years. However, there are still few efforts in designing task-specific ionic liquids for the selective capture of H2S. In view of this situation, and on the basis of the results obtained from the pre-research in our group, it is proposed in this project to design dual Lewis-base functionalized ionic liquids (DLB-ILs) and use them to develop novel and creative methods for the selective capture of H2S. Keeping this idea in mind, it is suggested to investigate the dual Lewis-base functinalization of ionic liquids, the component formulation of DLB-IL intensified absorbents, the selective absorption of H2S in DLB-ILs or in DLB-IL intensified solutions, the transformation of H2S to sulfur by reacting with SO2 in DLB-IL intensified solutions, and also the integrated process of H2S capture with H2S transformation. To look into the steps or processes mentioned above, the phase equilibrium thermodynamics, kinetics, mass and heat transfer characteristics, and process technology are studied in detail to disclose the process mechanisms. It is believed that this project may provide important theory and methodology for the technology innovation of selective capture of H2S after successful implementation. This project is also featured with innovations in three aspects: the novel ionic liquids species with dual Lewis-base groups, the reactive transformation of H2S in DLB-IL intensified solutions, and the integration of H2S capture with its transformation to regenerate the absorbent by using the DLB-IL intensified solution as the unique medium in both steps.

选择性捕获H2S是能源深加工利用过程节能减排的重点和热点。已有捕获方法存在能耗高、H2S与CO2间的分离选择性低、吸收剂挥发污染环境等缺陷。用离子液体作为吸收剂是目前H2S捕获研究的新动向，但为H2S捕获而专门设计功能化离子液体却鲜见报道。本项目经前期预研，提出用双Lewis碱性功能设计的离子液体（简称DLB-IL）来创新H2S捕获方法的新思路。围绕该思路，展开离子液体的双Lewis碱性功能设计、DLB-IL增强的混合吸收液构筑、H2S的选择性吸收、H2S与SO2在DLB-IL混合液中的反应转化等分过程及其集成过程的研究，考察过程涉及的热力学相平衡、动力学、传递特性、及过程工艺特征等，阐明过程机理，为H2S高选择性捕获方法创新奠定重要的理论和方法基础。本项目在离子液体新物种设计、H2S在离子液体中与SO2的反应转化、H2S捕获-反应转化-吸收液再生的过程集成等方面有特色和创新。

选择性捕获H2S是能源深加工利用过程节能减排的重点和热点。已有捕获方法存在能耗高、H2S与CO2间的分离选择性低、吸收剂挥发污染环境等缺陷。用离子液体作为吸收剂是目前H2S捕获研究的新动向，但为H2S捕获而专门设计功能化离子液体却鲜见报道。本项目提出用双Lewis碱性功能设计的离子液体（简称DLB-IL）来创新H2S捕获方法的新思路。围绕该思路，展开离子液体的双Lewis碱性功能设计、DLB-IL增强的混合吸收液构筑、H2S的选择性吸收、H2S与SO2在DLB-IL溶液中的反应转化等分过程及其集成过程的研究，考察过程涉及的热力学相平衡、动力学、传递特性、及过程工艺特征等，阐明过程机理。经4年潜心研究，设计、合成、并表征了30多种Lewis碱性设计的离子液体，其中双Lewis功能化离子液体近10种。测定了这些离子液体及其部分溶液吸收H2S、CO2及其它气体的气液平衡或膜渗透数据，比较了这些离子液体的吸收选择性，发现部分离子液体的H2S/CO2选择性可高达几十，甚至上百。实验、理论计算结合机理分析的研究表明，离子液体对H2S的高吸收选择性主要来源于适度的双Lewis碱性设计，质子型离子液体或非质子型离子液体的氢键受体化设计都对提高H2S的吸收选择性有益。考察了Lewis碱性设计的几种离子液体溶液分别吸收H2S、CO2、SO2等过程的热力学、动力学、和传递特性，积累了一批基础数据。此后，重点探索了H2S和SO2在离子液体或其溶液中的反应转化过程，H2S可在数分钟内达到96%以上的转化率，表明离子液体可取代传统的有机溶剂作为Claus过程的反应介质或催化剂。最后，初步探索了H2S在离子液体中的捕获与反应转化一体化过程，开发了一种具重要应用前景的离子液体促性的液相Claus工艺过程。本项目在双Lewis碱性离子液体新物种设计、H2S在离子液体中与SO2的反应转化、H2S捕获与转化的过程集成等方面有重要创新，为能源气中的H2S高效捕获与清洁利用奠定了重要的理论和方法基础。