Abstract:
The invention relates to a process for working-up a reaction mixture (5) comprising polyetherol and dissolved alkali metal comprising catalyst, wherein at least alkali metal ions of the dissolved alkali metal comprising catalyst are partially or completely removed from the mixture by a membrane separation process, the process comprising following steps: (a) feeding the reaction mixture (5) comprising polyetherol and dissolved alkali metal comprising catalyst into a first chamber (1) of a separation unit (3), (b) feeding a solvent into a second chamber (7) of the separation unit (3), the first chamber (1) and the second chamber (7) being separated by a membrane (9), (c) transporting at least the alkali metal ions of the alkali metal comprising catalyst from the first chamber (1) into the second chamber by passing through the membrane (9).