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Zusammenfassung:
Hybrid sol–gel catalysts of zinc hexacyanocobaltate and SiO2 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 molSO (molZn h)−1) and high productivity (575 gPolymer gCatalyst
−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 nZn/nCo = 2.1, whereby the double metal cyanide was closely associated with silica.
