Hybrid sol-gel double metal cyanide catalysts for the copolymerisation of styrene oxide and CO sub(2)

Hybrid sol-gel catalysts of zinc hexacyanocobaltate and SiO sub(2) were prepared by co-precipitation of the double metal cyanide with silica. Hybrid catalysts prepared at moderately acidic conditions showed the best performance with respect to activity, selectivity and stability. The hybrid sol-gel materials displayed high catalytic activity for the copolymerisation of styrene oxide and carbon dioxide (up to 650 mol sub(SO) (mol sub(Zn) h) super(-1)) and high productivity (575 g sub(Polymer) g sub(Catalyst) super(-1)). They also displayed good selectivity to the polymeric product (80-87%), while only little cyclic styrene carbonate was formed as side product. A detailed electron microscopy study of the hybrid sol-gel materials showed that the active phase consisted of thin platelets containing the metals in a molar ratio n sub(Zn)/n sub(Co) = 2.1, whereby the double metal cyanide was closely associated with silica.