Abstract: Double metal cyanide complexes based on Zn₃[Co(CN)₆]₂ were prepared by precipitate transformation from precursors such as ZnO,Zn(OH)₂,ZnCO₃,and basic ZnCO₃,and the effect of preparative method on the catalytic efficiency towards copolymerization of propylene oxide and CO₂ was investigated.The results show that DMC catalyst with Zn(OH)₂ as precursor exhibits highest catalytic efficiency of  over 4 400 g/g,which is about double catalytic efficiency compared with complexes derived from solution precipitation method.The morphology of this precursor has significant impact on resulting catalytic efficiency,the phase Zn₅(OH)₈Cl₂·H₂O produced by precipitating reaction of ZnCl₂ and  NaOH can be transferred effectively into active site of catalyst to afford highly active catalyst with high crystalinity.The study also shows that catalytic efficiency of final catalyst relates to average particle size of precursor,the catalytic efficiency decreases sharply while average particle size of precursor is great than 75 μm.

Key words: zinc hexacyanocobaltate, zinc hydroxide, catalyst, copolymerization