Rapid conversion of CO2 and propylene oxide into propylene carbonate over acetic acid/KI under relatively mild conditions

The coupling of CO2 and epoxides to form cyclic carbonates has been industrialized since the 1960s. The employment of an efficient and low-cost catalyst is one of the decisive factors to improve the production efficiency. Many catalysts with high activities have been developed; however, those that can convert CO2 and epoxides into cyclic carbonates in a short time or with high efficiency are still less reported. In this study, we developed such an efficient and low-cost catalytic system of hydrogen bond donor acetic acid (AA) in combination with KI (denoted as AA/KI) for the rapid conversion of CO2 and propylene oxide (PO). The optimal reaction condition for AA/KI catalyzing the coupling of CO2 and PO is screened by trial and error. Atime-dependent PO conversion study showed that the AA/KI catalytic system displays quite high activity to completely convert PO within a short time of 15 min under optimized conditions (0.9 MPa CO2 and 90 degrees C) for the best case. Moreover, AA/KI is also active for the coupling of other epoxides with CO2, and the reaction efficiency is significantly influenced by the electronic and steric effects of the epoxide substrates. In addition, the plausible mechanism was deduced. Herein, we provide an efficient and relatively mild route to catalyze the coupling of CO2 and epoxide within a short time using a non-toxic, cheap and facile catalyst.

Automated summary

The study developed an efficient and low-cost catalytic system of AA/KI for the rapid conversion of CO2 and propylene oxide. The catalytic system showed high activity in completely converting propylene oxide within 15 minutes, with potential applications in the coupling of other epoxides with CO2 as well. The reaction efficiency was found to be significantly influenced by the electronic and steric effects of the epoxide substrates.