Metal-free catalysts for the synthesis of cyclic carbonates through the reaction of CO2 with epoxides
Jing Chen's PhD project focuses on developing cost-efficient and highly active metal-free catalytic systems for the synthesis of cyclic carbonates from CO₂ and epoxides. To achieve this, Chen tested inexpensive dyes containing active species (Cl⁻) as catalysts for the reaction. To further enhance their catalytic activity, Chen empoyed strategies such as substituting the counteranion and introducing a hydrogen-bond donor (HBD), yielding a series of dye-based organocatalysts with significantly improved performance.
Subsequently, the immobilisation of dye-based catalysts on SiO₂ supports was carried out. However, the resulting heterogeneous catalysts suffered from the leaching of active sites. To obtain more stable heterogeneous systems, Chen tested various resin beads containing I⁻ in this reaction, some of which were also functionalised with an HBD group. Among them, NIP-I demonstrated the highest catalytic activity in its powder form. Moreover, this catalyst maintained steady performance in a fixed-bed reactor for 12 h of time-on-stream.
In conclusion, Chen demonstrates a successful strategy for enhancing the catalytic activity of dye-based catalysts in the CO₂ cycloaddition with epoxides to form cyclic carbonates. Additionally, she developed an inexpensive, efficient, and stable heterogeneous catalyst.