Process for the preparation of DMC catalysts

Abstract

The invention provides an improved process for the preparation of double metal cyanide (DMC) catalysts for the preparation of polyether polyols by polyaddition of alkylene oxides on to starter compounds containing active hydrogen atoms, in which aqueous solutions of a metal salt and a metal cyanide salt are first reacted in the presence of an organic complexing ligand and optionally one or more further complex-forming components to form a DMC catalyst dispersion, this dispersion is then filtered, the filter cake is subsequently washed with one or more aqueous or non-aqueous solutions of the organic complexing ligand and optionally one or more further complex-forming components by a filter cake washing and the washed filter cake is finally dried, after an optional pressing out or mechanical removal of moisture.

1 - 11 . (Cancelled).  
     
     
         12 . A process for preparing a double-metal cyanide catalyst comprising: 
 combining with a mixing nozzle in the presence of at least one organic complexing ligand, 
 (a) at least one aqueous solution of at least one metal salt; with  
 (b) at least one aqueous solution of at least one metal cyanide salt;  
 to form a double-metal cyanide catalyst dispersion;  
   filtering the double-metal cyanide catalyst dispersion to obtain a filter cake;    washing the filter cake at least once with the at least one organic complexing ligand by a filter cake washing;    mechanically removing moisture in the washed filter cake; and    drying the filter cake    wherein the steps of filtering, washing and mechanically removing are conducted in a filter press.    
     
     
         13 . The process according to  claim 12 , wherein the metal salt is zinc chloride.  
     
     
         14 . The process according to  claim 12 , wherein the metal cyanide salt is potassium hexacyanocobaltate.  
     
     
         15 . The process according to  claim 12 , wherein the organic complexing ligand is tert-butanol.  
     
     
         16 . The process according to  claim 12 , wherein the steps of filtering, washing mechanically removing and drying are conducted in a filter press.  
     
     
         17 . The process according to  claim 12 , wherein the mixing nozzle is a jet disperser.  
     
     
         18 . The process according to  claim 12 , wherein the mixing nozzle has slits therein.  
     
     
         19 . The process according to  claim 12 , wherein the step of washing is flow through washing.  
     
     
         20 . The catalyst made by the process according to  claim 12.