Recovery of double metal cyanide complex catalyst from a polymer

Abstract From the Canadian patent

A process for recovering double metal cyanide complex catalyst from a polymer such as polypropylene glycol in a form suitable for use as a polymerization catalyst is described. The process comprises the steps of (a) combining the polymer with a non-polar solvent to precipitate the catalyst and (b) filtering the resulting mixture in the presence of a filter aid to separate the polymer from the precipitated catalyst. In contrast to the prior art methods of catalyst removal, the process of the invention yields polymer uniformly low in color as well as recovered catalyst which may be reused in subsequent polymerizations.