Effect of Zn/Co initial preparation ratio in the activity of double metal cyanide catalysts for propylene oxide and CO2 copolymerization

Zn-Co double metal cyanide (DMC) catalysts were prepared by varying the initial amounts of ZnCl₂ to analyze the influence of method of preparation on the different copolymerization parameters. Synthesized catalysts were analyzed by different techniques, infrared spectrometry and inductively coupled plasma optical emission spectrometry, scanning electron microscopy, N₂-physisorption and X-ray diffraction to determine whether characteristics affect the catalytic activity. The copolymers were characterized by infrared spectrometry and gel permeation chromatography. Highly active catalyst (2.5 kg polymer/g catalyst) was synthesized, low amounts of cyclic carbonate byproduct were produced (0.4%) with medium crystallinity catalysts and considerable amounts of K⁺ (0.4–1.0 wt%).