功能离子液体和聚乙二醇的设计合成及其移动CO2转化反应平衡的研究

Utilization of CO2 as a feedstock to produce value-added chemicals and fuels is of great importance. Overcoming thermodynamic limitation of the reactions is the key to CO2 conversion. In this project, two approaches are proposed for transformation of CO2 to CO, aldehyde, alkyl carbonate, and methyl formate. One is using diol functionalized ionic liquid (IL) and PEG for CO2 conversion indirectly (reactions using urea as raw material for producing chemicals and ammonia), which will be designed and synthesized. Diol functional IL and PEG react with urea producing high energy level carbonate intermediate and ammonia, hydrogenation of the carbonate intermediate can produce CO, and CO will be further transformed into aldehyde directly, IL and PEG are regenerated at the same time. The other route is using IL and PEG functionalized with carbodiimide (water absorbing group), which will be designed and synthesized. Using them as water absorption reagent can enhance the equilibrium conversion in CO2 transformation to alkyl carbonate, methyl formate and CO, and the IL and PEG can be regenerated after dehydration. The effects of different factors, such as structure of the IL and PEG, property of the catalyst, composition of the system, pressure, temperature on the conversion and selectivity will be studied. The influence of IL and PEG on reaction equilibrium will be studied quantitatively, which is instructive for developing new routes to overcome the thermodynamic limitation for CO2 conversion.

CO2的资源化利用是重大研究课题。解决反应受热力学限制问题对于CO2转化利用极为重要。本项目提出两种途径解决CO2转化为CO、醛类物质、烷基碳酸酯、甲酸甲酯平衡转化率低的问题。1）为提高CO2间接利用(以尿素为原料生成化学品和氨的反应)的平衡转化率，设计合成带有邻二羟基功能化离子液体(IL)和聚乙二醇(PEG)。功能化IL、PEG与尿素反应生成能量较高的碳酸酯中间体和氨，中间体加氢生成CO或CO进一步转化为醛，同时IL、PEG得到再生。2）设计合成带有碳二亚胺(吸水基团)的IL和PEG，用于吸收CO2转化为烷基碳酸酯、甲酸甲酯、CO反应中生成的水移动反应平衡，吸水后的IL和PEG可脱水再生。深入研究IL和PEG结构、催化剂的性质、体系的组成、压力、温度等对平衡转化率和选择性的影响规律和机理，定量研究IL和PEG对化学平衡的移动作用和规律，为解决这些重要反应热力学受限问题提供新方法和新途径。

CO2是最主要的温室气体，它的吸收和转化对于实现碳中和(Carbon neutral)目标具有重要意义。CO2作为C的最高氧化态，能量低，许多CO2参与的反应受到热力学的限制。在功能离子液体和聚乙二醇的设计合成促进二氧化碳转化的基础上，研究了不同物质对二氧化碳转化平衡的影响。利用碳化钙产生乙炔中多余的能量促进二氧化碳与甲醇反应合成碳酸二甲酯。在生产乙炔的同时，碳化钙可以有效的提高碳酸二甲酯的产率，可以使甲醇的转化率从1%提高到11%。尿素作为二氧化碳替代物与甘油反应生成甘油碳酸酯反应中，微波能够有效地促进反应的进行，可以在较短的时间内实现94%的产率。常温常压下，AgCl与离子液体体系可以有效地催化CO2转化合成不对称碳酸酯可在短时间内达到100%的产率。设计了一种无碱条件下连续合成甲酸的方法，体系工作稳定高效。金纳米颗粒可以在140摄氏度下有效催化CO2、H2合成甲醇。实现了在较低温度下直接利用碳化钙为炔源，不经乙炔直接合成炔类化合物。本项目在ChemSusChem、Chem. Commun.、ChemCatChem、Pure Appl. Chem.、Chem. Select等刊物上发表论文5篇，另有3篇在投，申请专利2项。培养博士1名、在读博士1名、出站博士后1名。