Direct synthesis of propylene carbonate from propylene and carbon dioxide catalyzed by quaternary ammonium heteropolyphosphatotungstate–TBAB system

In this paper, we have developed a highly efficient method for the direct preparation of propylene carbonate from propylene and carbon dioxide (CO2) using quaternary ammonium heteropolyphosphatotungstate–quaternary ammonium halide catalytic system with anhydrous hydrogen peroxide as an oxidant through one-pot two-step process. The effects of the amount of tetrabutylammonium bromide (TBAB), the concentration of hydrogen peroxide and other reaction conditions were investigated. The catalyst system gave an optimum propylene oxide yield (91%) at 75 °C in oxidation step and the highest propylene carbonate yield (99%) at 140 °C and 3.0 MPa in cycloaddition step. Based on the results, a reaction mechanism has been proposed.

In this study, we successfully combined the epoxidation of propylene catalyzed by reaction-controlled phase-transfer quaternary ammonium heteropolyphosphatotungstate and the cycloaddition of CO2 to propylene oxide through one-pot two-step process.Figure optionsDownload full-size imageDownload as PowerPoint slide