Efficient high-throughput screening for the preparation of propylene carbonate in a supercritical microchannel continuous flow system

Abstract

With the intensification of the global greenhouse effect, the utilization and fixation of CO₂ has become one of the most important research fields in our world. However, there are still enormous challenges in achieving efficient fixation and conversion of carbon dioxide into high-value chemicals. Herein, the cycloaddition reaction strategy is adopted to achieve the fixation of supercritical carbon dioxide (SC-CO₂) and the high-value conversion of carbon resources to propylene carbonate (PC) by using propylene oxide (PO) as the reaction precursor. Under tetrabutylammonium bromide (TBAB) as a catalyst and water (H₂O) as a green solvent, the reaction factors, such as reaction temperature, reaction pressure, catalyst amount, water concentration and molar ratio of reactants, is conducted through the high-throughput screening technology to explore the catalytic performance in a self-designed microchannel reactor. The results indicate that the yield of PC can reach 91.82 % (along with a high selectivity of 99.12 %) at a reaction temperature of 160 ℃, reaction pressure of 8 MPa, catalyst amount of 0.72 mol %, reactants molar ratio of 8, and the residence time of 482 s. Besides, the thermodynamic and kinetic for carbonate synthesis are studied to fully understand the reaction process, and the activation energy of is explored. This work is more efficient than most similar reported works, which provide valuable insights into the practical application of CO₂ in the supercritical state combined with microfluidics for synthesizing high-value monomers.