Efficient Catalysts of Mixed Amino‐Functionalized Ionic Liquids and Zinc Halides for Cycloaddition of CO 2 to Propylene Oxide without Solvent

Amino‐functionalized halide ionic liquids, aminopropyl‐3‐butyl‐imidazolium ([Apbim] + ) with different halogen anions, and their zinc halide mixing catalysts were prepared and used to catalyze the cycloaddition of CO 2 to propylene oxide (PO) without solvent. Under ideal conditions, the conversion of PO could reach 93.5 % with the catalysis of [Apbim]Cl. Under optimized conditions of catalyst dosage, reaction temperature, CO 2 pressure, and reaction time, with the catalysis of [Apbim]I, [Apbim]Cl/ZnBr 2 (3:1), and [Apbim]Br/ZnBr 2 (5:1), the conversion of PO and the selectivity of propylene carbonate (PC) both reach > 99 %. From the point of view of preparation process and industrial operation, [Apbim]Cl/ZnBr 2 is the most suitable catalyst. This catalyst is characterized by good reusability and catalytic activity, and the yield of PC is about 99 % at least for ten times repeated use.