离子液体高效低能耗选择性脱硫新过程

High sulfur coals with over 1wt% sulfur content, which are going to be the main coal resource instead of low sulfur coals, can produce high concentration of SO2 ( > 5000 ppm). Although limestone scrubbing and amine scrubbing as two attractive approaches have been applied widely in industries, there still are some inherent drawbacks, such as unrecoverable SO2 resulting in serious waste of sulfur resources and high energy consumption. Therefore, the development of new low energy consumption technologies for efficient and reversible capture of SO2 is of critical importance. In recent years, capturing SO2 with ionic liquids (ILs) is believed as one of the effective methods, but there are also some drawbacks, such as lower gravimetric absorption capacity, higher viscosity and poor stability. In order to solve these problems, the two key issues of the intermolecular interactions between ILs and SO2 and quantitative structure-property relationship will be focused. By a combination of simulation caculations and experimental methods, the interaction site, mode and intensity between ILs and SO2 will be systematically studied, and the interaction mechanisms will be obtained from the micro scale and molecular level. The project will also investigate the effect of cations and anions, clusters as well as interactions on physicochemical properties (such as thermal stability, viscosity) and SO2 absorption/desorption performances (such as gravimetric absorption capacity, selectivity and enthalpy), and establish the quantitative relationship of IL structures-physicochemical property-SO2 separation performances. Based on these studies, a series of novel functionalized pyridinium-based ILs with excellent absorption/desorption performances, high thermal stability, and low viscosity will be designed and synthesized. This project will provide theoretical guidance to develop a new energy saving technology for efficient and reversible capture and separation of SO2 by pyridinium-based ILs as absorbents.

中高硫煤逐渐替代低硫煤成为燃煤主体，导致其产生的SO2含量显著提高，传统脱硫方法已无法满足需求，如石灰石/石膏法SO2不可回收，硫资源严重浪费；有机胺法能耗高等。因此，开发高效低能耗可回收SO2的脱硫新方法是解决当前问题的关键。本项目拟利用离子液体结构和性质可精细调控、几乎不挥发的特点，重点围绕离子液体-SO2间相互作用机制和离子液体构效关系展开。结合实验表征与模拟计算，研究SO2与离子液体相互作用位点、方式和强度，获得离子液体与SO2间微观作用机理；研究阴阳离子、团簇结构、相互作用对其物性（稳定性、粘度等）和SO2吸收/解吸性能（质量吸收量、选择性和吸收焓等）的影响，建立离子液体结构-性质-分离性能定量关系。在此基础上，设计合成系列SO2吸收量大、易再生、选择性高、物化性质稳定、粘度低的吡啶类离子液体，为形成高效低能耗SO2分离新技术提供理论基础。

本项目针对现有离子液体粘度高、稳定性差及SO2吸收量低等难题，围绕离子液体构效关系和离子液体-SO2间作用机理、吡啶类功能离子液体设计合成、吸收过程中离子液体的物性动态变化规律展开系统研究。与阳离子相比，阴离子结构对SO2 吸收性能影响更为明显，其中阴离子与SO2间静电作用较强的[C4Py][SCN]表现出高的质量吸收量0.841 gSO2·gIL-1；在此基础上，在阳离子上引入碱性或极性基团，设计合成了叔胺基、腈基和醚基功能离子液体。其中叔胺基离子液体不仅在常压条件下表现出最高的SO2吸收量约1.06 gSO2g·IL-1，在0.01 MPa条件下也能达到0.37 gSO2g·IL-1，明显高于大多数所报道的功能离子液体吸收量。腈基离子液体对SO2/CO2的选择性最高约为79，较[C4Py][SCN]对SO2/CO2的选择性提高近41%。吸收过程中常规离子液体粘度呈单一下降趋势，而功能离子液体粘度呈现先增加后降低的特殊规律，揭示了化学吸收过程离子-SO2成簇导致粘度增加，物理吸收过程SO2破坏离子间缔合造成粘度降低的科学本质，为设计高效离子液体提供了理论指导。.项目执行期间，在Chem Rev, Green Chem, ChemsusChem, Ind Eng Chem Res等期刊发表论文12篇，申请/授权专利7项，参编英文书章节1章，参加国际/国内学术会议并作主题/邀请/口头/墙报报告5次。项目负责人入选2017年“中科院过程所青年创新促进会”，2018年“中科院青年创新促进会”，2019年获得AIChE “Young Investigator Award for Innovations in Green Process Engineering”，入选“所过程优青”，项目1名成员提升为副研究员，培养博士/硕士生共4名。