| 摘要 |
A filtration method is disclosed for recovering purified polyether polyol comprising the steps of providing an aqueous solution of a polyether polyol containing an alkali metal catalyst residual formed from a transesterification process utilizing an alkali metal catalyst, contacting the aqueous solution with a stoichiometric excess of magnesium sulfate, magnesium sulfite or a combination thereof to form a second aqueous solution, wherein said stoichiometric excess is based on the amount of said alkali metal catalyst residual. Water is removed from the second aqueous solution at a temperature above a set limit of said polyether polyol to produce a dehydrated slurry containing a polyether polyol phase substantially free of residual alkali metal and a precipitated solid phase comprising sulfate and/or sulfite salts of the alkali metal catalyst, magnesium hydroxide, and excess magnesium sulfate and/or sulfite, wherein the particle size distribution of said precipitated solid phase is controlled to minimize the amount of particles therein that are smaller than 3 microns. The dehydrated slurry is then passed through a filtration system to separate the polyether polyol phase from the precipitated solid phase. |
