Prussian Blue Analogs As Catalysts for the Fixation of CO2 to Glycidol to Produce Glycerol Carbonate and Multibranched Polycarbonate Polyols

A series of Prussian blue analogs (PBAs) having a range of crystal structures and compositions was investigated as heterogeneous catalysts for the fixation of carbon dioxide (CO2) to glycidol. The morphology of PBAs was modified, as confirmed by structural characterization, by varying the precipitation method. Of the prepared catalysts, the cubic Zn(II)-Co(III) PBA exhibited the highest catalytic activity (turn-over frequency up to 763 h-1), selectivity (up to 94%), and recyclability for the cycloaddition of CO2 to glycidol. In addition, branched polycarbonate polyols having tunable branching degree (0.15-0.61) and linear polycarbonates of relatively high carbonate content (up to 64.2%) were produced via ring-opening (multibranching) copolymerization of CO2 and various epoxides using a highly amorphous Zn(II)-Co(III) double metal cyanide catalyst. Mechanistic pathways have been proposed by combining experimental results with computational studies.