(622d) Design of Amine-Based Catalytic Polymeric Membranes through Structural Modification for Integrated CO2 Capture and Conversion

Reducing Carbon Dioxide (CO₂) concentration in the atmosphere is a major global challenge that requires major improvement and innovation. Integration of CO₂ capture (from air or concentrated point sources) and CO₂ conversion into a single unit process using a catalytic membrane potentially offers a more energy-efficient and cost-effective alternative to current sorbent-based processes. We present poly(4-vinyl)pyridine (P4VP) based membranes are permeable and selective for CO₂ separation from mixed gases and catalytically active for cyclic carbonate synthesis at mild temperatures. The nitrogen functional group in P4VP selectively captures and concentrates CO₂ at the catalytic interface for CO₂ reduction reactions. Furthermore, P4VP can be modified molecularly, tuning its CO₂ separation performance and catalytic activity. This work shows how different modifications impact these performances for the model reaction of cyclic carbonate synthesis from CO₂ and epichlorohydrin (ECH), an epoxide. Quaternized P4VP samples that vary in Carbon chain length were prepared and their catalytic activity in dry and wet conditions was measured with a batch reaction. Cyclic carbonate production rate increased with Carbon chain length but also solubility of the catalyst into the epoxide, thus is unfit for membrane testing. Catalytic performance decreased in wet conditions because the halogen in the quaternized P4VP has too much nucleophilicity, presenting interfering interactions with water, decreasing performance. Catalyst samples using the halogen below the previous one resulted in increased catalytic performance in wet conditions due to the lower nucleophilicity. Finally, incorporation of metals in different ways in the catalyst design was studied which resulted in increased performance and recovery, which is very promising for membrane testing. This study could lead to the development of more rational designs of highly efficient bifunctional membranes with effective CO₂ capture and conversion to study more complicated CO₂ conversion reactions and develop next generations of catalytic membranes.