Synthesis of propylene carbonate (PC) from CO₂ and propylene oxide catalyzed by potassium halide (KCl, KBr, KI) in the presence of inorganic ammonium salt (ammonium carbamate, ammonium bicarbonate, ammonium carbonate) was studied. It was discovered that potassium halide and inorganic ammonium salt showed excellent synergetic catalytic effect, and ammonium carbamate showed the best co-catalytic effect among of them when KI was used as main catalyst for PC synthesis. Effects of amount of catalyst, reaction temperature, CO₂ initial pressure, amount of pre-added PC and reaction time on PC synthesis were also examined. Under the optimal reaction conditions, over 99% of PC yield was obtained.

Key words: carbon dioxide, propylene oxide, propylene carbonate, potassium iodide, inorganic ammonium salt