DESIGN OF AMINE-BASED CATALYTIC POLYMERIC MEMBRANES THROUGH STRUCTURAL MODIFICATION FOR INTEGRATED CO2 CAPTURE AND CONVERSION

Amine-based catalysts hold significant promise for CO2 conversion into value-added cyclic carbonates due to their 100% atom economy, low energy demands, cost efficiency, and eco-friendly nature. However, their broader application under mild conditions is hindered by a limited understanding of structure-performance relationships. This work investigates the structural modification of poly(4-vinylpyridine) (P4VP) through quaternization with alkyl-halides to enhance catalytic performance and recovery. Catalysts were tested in a batch reactor with epichlorohydrin (ECH) and CO2 at mild temperatures (57°C), producing chloroprene carbonate. Results show that catalytic performance improves with increasing alkyl chain length due to enhanced solubility in ECH and weakened pyridinium-halide interactions — though longer chains reduced catalyst recovery. Counterion strength also played a pivotal role: iodine (I), with lower electronegativity, outperformed bromine (Br) by increasing catalytic availability and minimizing water interactions, enhancing hydrogen bond donor (HBD) effectiveness. This foundational work supported further functionalization efforts.

The second part investigates P4VP-metal complexes for CO2 conversion, aiming to enhance catalytic performance and recovery. Catalysts were synthesized and evaluated under identical conditions. Results highlighted that performance depended on metal type, pyridine structure, counterion, and pyridine-to-metal ratio. A synergistic effect was observed uniquely with cobalt complexes, with P4VP-CoCl2 showing twice the production rate of P4VP-CoCO3. The pyridine structure’s strong interaction with cobalt contributed to this synergy, while an ideal P4VP-to-CoCl2 ratio of 4:1 maximized catalytic efficiency. These findings provide crucial insights into structural modifications and counterion selection, laying the groundwork for next-generation, high-performance amine-based catalysts with enhanced functionalities for complex CO2 conversion reactions.