Preparation and Activity of CeO2 Nanoparticles in Synthesis of Polycarbonates from CO2

Direct polymerization of CO2 with diols for synthesis of carbonates represents a sustainable and efficient approach for CO2 utilization, in which CeO2 exhibits favorable catalytic properties in the reaction system. In this study, nanometer-sized CeO2 catalysts were synthesized via a hydrothermal method utilizing NaOH as precipitating agent. The effects of sintering temperatures (500, 600, and 700 degrees C) and surfactants (cationic, anionic, and nonionic) on structural and physicochemical properties of CeO2 were thoroughly investigated. When the sintering temperature was 600 degrees C, CeO2 displayed an optimal crystallinity and a higher concentration of defect sites compared to the other temperatures. The surfactants significantly increased oxygen vacancy concentration on the surface of CeO2, leading to a maximum CO2 uptake of 0.532 mmol/g at 25 degrees C. Building upon these findings, a series of synthesized CeO2 catalysts were applied in the one-step synthesis of polycarbonate from CO2 and diol, resulting in significant improvements in both conversion and selectivity within the reaction system. The results demonstrated that catalytic activities of CeO2 prepared at various sintering temperatures with different surfactants displayed notable differences. Notably, the CeO2 catalyst sintered with cetyltrimethylammonium bromide (CTAB) as the surfactant at 600 degrees C exhibited the highest catalytic activity and selectivity, achieving a conversion of 91.0% for 1,6-hexanediol and a selectivity of 76.6% for poly(6-hydroxyhexyl) carbonate. The outstanding catalytic performance of CeO2 with the high yield can be primarily attributed to its favorable structural characteristics, abundant defect sites, and high CO2 uptake capacity.