吸收氨的多位点离子液体构效设计及工程基础研究

Ammonia is one of the typical toxic and hazardous industrial gaseous pollutants. Ammonia is also one of the most important basic chemical products and indispensable industrial raw materials. Ammonia tail gas (NH3, H2, O2, N2 etc.) is mainly treatment by using dilute sulfuric acid absorption to produce ammonium sulfate in the industry. This technology becomes a huge burden due to strong corrosive, large amount of waste water, low value-added products and limited market in China. This project proposed a new idea for recovery of ammonia by using multi-site ionic liquids. By designing the multi-site’s acidity of ionic liquids, the absorption capacity, selectivity and desorption of NH3 were controlled. Based on this theory, the functionalized ionic liquids were prepared and can recovery NH3 efficiently from tail gas. Through the experimental characterization and simulation method, interaction is obtained between ammonia and the microstructure, acidic sites and hydrogen of ionic liquid. Physical properties of ionic liquids and the thermodynamic data of tail gas in ionic liquids will be investigated to establish a thermodynamic model based on molecular parameters. The interfacial properties of ammonia adsorbed by ionic liquids will be investigated. New mass transfer model of ammonia in ionic liquid will be obtained, and the influence mechanism of ionic liquid on ammonia absorption process will be clarified. The continuous experiment will be carried out to obtain the effects of ionic liquid on the process of ammonia absorption and desorption. Ionic liquid cycle performance and the best operation parameters will be tested. That will provide theoretical and engineering basis for designing multi-site ionic liquids and developing new NH3 separation technology.

氨是典型有毒有害工业气态污染物之一，同时氨也是重要的化工原料。工业上含氨尾气（NH3、H2、O2、N2等）主要利用稀硫酸处理，由于腐蚀性强，废水量大，产品附加值低且市场有限，为企业带巨大负担。本项目提出了多位点离子液体净化含氨尾气回收氨的新思路。通过设计离子液体中多位点的酸性强弱，调控NH3的吸收容量、选择性和吸收剂的再生性能，设计开发出高效回收NH3的功能化离子液体。通过实验表征和模拟相结合方法，获得离子液体的微观结构、酸性位点、氢键和氨之间的相互作用规律；研究离子液体的物性和各气体组分在离子液体中的相平衡数据，建立基于分子参数的热力学模型；考察离子液体吸收氨表界面性能，获得氨在离子液体中传质新模型，阐明离子液体对氨吸收过程的影响机制；完成离子液体吸收-解吸氨过程的连续实验评价，获得吸收剂的循环性能和最佳工艺参数，为高效选择性分离氨的吸收剂设计及新工艺的开发提供理论和工程基础。

氨是典型有毒有害工业气态污染物之一，同时氨也是重要的化工原料。工业上含氨尾气（NH3、H2、O2、N2等）主要利用稀硫酸处理，由于腐蚀性强，废水量大，产品附加值低且市场有限，为企业带来巨大负担。本项目提出了多位点离子液体净化含氨尾气回收氨的新思路，设计合成了多种功能化离子液体，进行了离子液体结构表征和物性测定得出结论：质子型离子液体随着温度升高，离子液体密度和粘度均降低；含钴配合物Lewis型离子液体随着温度增加密度略微有所降低，而粘度则大幅降低。研究了功能化离子液体不同位点和氢键结构与NH3之间的相互作用的影响规律得出结论：质子型离子液体NH3吸收机理为质子氢可以先后与两分子NH3形成氢键作用；含金属配合物的Lewis型离子液体具有较高的NH3吸收量主要是因为金属离子与NH3间的化学络合作用；咪唑类DPILs离子液体对NH3的吸收过程的相互作用可以分为两种，首先是离子液体对NH3的化学吸收捕集作用，随着化学吸收达到平衡，离子液体主要通过物理吸收作用对NH3进行吸收。另外开展了含氨尾气中各组分气体在离子液体中的相平衡实验，建立离子液体多元体系的相平衡预测模型。通过实验表征和模拟相结合，完成离子液体吸收氨的机理分析，获得如下规律：NH3在吡啶类DPILs中的溶解度随着温度的升高而降低，随着压力的增大而升高；吡啶类离子液体吸收NH3过程的ΔrHm绝对值的大小对应NH3溶解度的顺序。完成了离子液体吸收-解吸氨过程的连续实验评价，获得了吸收剂的循环性能和最佳工艺参数，为高效选择性分离氨的吸收剂设计及新工艺的开发提供理论和工程基础。