新型中空纤维膜渗透与低温相变复合的CO2捕集机理研究

CO2 capture, storage and utilization is one of the dominant methods to mitigate the issue of climate change and air pollution. Nowadays, capital cost and energy consumption are the dominant challenge of the existing CO2 capture technologies. In this proposal, a novel hybrid CO2 capture process by integrating hollow fiber membrane and cryogenic phase change is developed. Compared to the conventional hybrid membrane-cryogenic CO2 capture processes, its advantage is that membrane treatment is carried out under low temperature condition. Then, CO2 is recovered by phase change under cryogenic condition. Finally, an optimal integration between membrane and cryogenic can be realized, which can achieve a better CO2 capture performance. The detail research will focus on the critical issues of novel hybrid CO2 capture technology. The objective is to understand: 1) the variation of properties for membrane under low temperature condition, and its influence on the molecular dynamics of gases. 2) The phase change of CO2 in cryogenic unit and its thermodynamic properties. 3) The relationship between membrane and cryogenic unit. The implementation of the proposal will be benefit to develop a noval direction for energy saving CO2 capture technology, and provide a theoretical guidance for the mitigation of air pollution issue.

CO2捕集、封存和再利用是解决气候变化及大气污染等焦点问题的有效措施。针对现有CO2捕集成本投入大、能耗高等问题，本课题拟提出一种新型中空纤维膜渗透与低温相变复合的CO2捕集方法。区别于二者的简单串联，本方法利用低温调控膜材料的表面特征及内部构效，促进膜材料的选择渗透性能，并在常压下通过低温相变将CO2从燃烧废气中捕集。膜渗透与低温相变技术的一体化耦合，可以更加有效地发挥二者的优势，提高CO2的分离效率且降低捕集能耗。课题将针对复合CO2捕集技术中的关键科学问题，从能源、材料与化工的交叉领域出发，深入分析膜材料在低温条件下各层次结构及选择透过性的变化规律，探讨低温CO2相变过程的热动力学特性及各相间质量、能量迁移机理，建立膜渗透与低温相变技术间的协同作用机制。本课题的实施有利于开拓CO2捕集技术的新思路，对解决大气污染等环境问题具有重要的理论指导意义。

CO2捕集、封存和再利用是解决气候变化及大气污染等焦点问题的有效措施。针对现有CO2 捕集成本投入大、能耗高等问题，本课题提出了一种新型中空纤维膜渗透与低温相变复合的CO2捕集方法。区别于二者的简单串联，本方法利用低温调控聚酰亚胺膜材料的表面特征及内部构效，促进膜材料的选择渗透性能，并在常压下通过低温相变将CO2从燃烧废气中捕集。研究结果表明，当操作温度降低至−20℃且进气压力控制在0.7 MPa时，聚酰亚胺膜材料的CO2选择性可以提升166%而渗透性仅降低31%。同时，CO2回收率可以提升至92%，有利于减少后续低温相变的成本。此外，液化天然气（LNG）冷能回收也为低能耗低温CO2捕集提供了一定条件。模拟结果显示，在液化天然气冷能高效回收再利用的前提下，CO2的捕集能耗可以降低至0.8MJ。本课题得到的研究成果，为开发新型低能耗CO2捕集技术提供了新思路，对解决大气污染等环境问题、生物沼气提纯等清洁能源问题具有重要的理论指导意义。