(646b) Tuning Amine-Based Polymer Catalyst for CO2 Conversion through Structural Modification Via Quaternization

Reducing Carbon Dioxide (CO₂) concentration in the atmosphere is a major global challenge that requires major improvement and innovation. Integration of CO₂ capture (from the 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-vinylpyridine) (P4VP) based membranes which 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 reaction, producing more valuable products. Furthermore, the quaternization of P4VP with alkyl halides can tune CO₂ separation performance and catalytic activity. We focus on how various degrees of quaternization impact the catalytic activity of P4VP for the model reaction of cyclic carbonate synthesis from CO₂ and epichlorohydrin (ECH), an epoxide. Quaternized P4VP with varying carbon chain length was prepared and their catalytic activity was measured with a batch reaction in dry and wet conditions. Cyclic carbonate production rate increased with respect to carbon chain length but also promoted solubility of the catalyst into the epoxide. Finally, catalytic performance decreased when operating at wet conditions due to the halogen present in the quaternized P4VP shielding the functional group from water, preventing it to perform as a Hydrogen Bond Donor (HBD). Therefore, catalyst samples using a different halogen were studied, resulting in increased catalytic performance in wet conditions due to the weaker intermolecular bond between this halogen and functional group. This study could lead to the development of more rational designs of a highly efficient bifunctional membrane with effective CO₂ capture and conversion and used to study more complicated CO₂ conversion reactions to further develop next generations of catalytic membranes.