CO₂ Capture and Conversion Based on Polymeric Membranes

The environment and economy can suffer various adverse effects from the rising concentration of CO₂ in the atmosphere, which is primarily due to the extensive combustion of fossil fuels like coal, oil, and natural gas for energy. To separate CO₂, membrane technology is extensively employed because of its low operating expenses and high energy efficiency. Despite the potential benefits of CO₂ separation and removal in reducing emissions, there are still risks associated with transporting and storing the collected CO₂, including the possibility of leakage and energy consumption. To address these challenges, this dissertation proposes an integrated CO₂ capture and conversion membrane system that utilizes amine-based facilitated transport membrane. This system not only separates CO₂ from the gas mixture but also converts the captured CO₂ into valuable chemicals under mild condition in situ. By integrating CO₂ capture and conversion into a single system, the energy consumption and costs associated with CO₂ transport and storage can be reduced.

To integrate CO₂ capture and conversion using a membrane-based system, our first step was to investigate the transport intermediates and kinetics of CO₂ in a typical facilitated transport membrane (PVAm membrane) using an operando surface enhanced Raman spectroscopy (SERS) platform and mathematical model. We then examined the formation of CO₂ transport intermediates in facilitated transport membranes with various chemical structures. Finally, we designed and constructed a membrane-based integration system capable of capturing and converting CO₂ to cyclic carbonate under mild conditions. Our polymeric membrane system was able to capture and convert CO₂ in a simulated flue gas even at a low CO₂ concentration of 1%, and at mild condition of 57 ℃ and 1 atm. This work provides a foundation for further studies and represents an important step towards achieving direct air capture and conversion with a polymeric membrane system, and it would also become an important step toward a more sustainable and efficient CO₂ management strategy.