Purification of Polyether Polyols Made by Double Metal Cyanide Catalysis

Purification of polyether polyols made by double metal cyanide catalysis was studied. The removal effect of residual double metal cyanide in the polyols by the methods of adsorption and precipitation-filtration is characterized by the residual concentration of the zinc and cobalt ions which is measured by Inductively Coupled Plasma Atomic Emission Spectrometry. Compared with precipitation-filtration, the method of adsorption was more practical and efficient for the purification of the polyols. And the optimum kind and amount of the adsorbent were obtained. The results showed that the combination of chelating fiber and attapulgus clay was the most favorable for the removal of zinc and cobalt ions and the appropriate weight ratio of chelating fiber and attapulgus clay was 1:1. The total concentration of zinc and cobalt ions can be reduced to lower than 1×10 -6 . And the amount of the adsorbent added was 3.33% by the weight of the polyether polyols. Also through Scanning Electron Spectroscopy the morphology of the chelating fiber was characterized before and after adsorption. The functional groups on the surface of the fiber could be coordinated with the catalyst attached to the polyol polymer chains to form the separable insoluble particles.