Method for the epoxidation of an olefin with hydrogen peroxide

A method for the epoxidation of an olefin, comprising:

• a) continuously reacting the olefin with hydrogen peroxide in a mixed reactor in the presence of a water soluble epoxidation catalyst comprising a manganese complex, wherein the reaction is carried out in a reaction mixture comprising an aqueous liquid phase and an organic liquid phase with mixing of the liquid phases;
• b) continuously withdrawing reaction mixture from the mixed reactor and separating the withdrawn reaction mixture into a separated aqueous phase and a separated organic phase;
• and
• c) continuously recycling part of the separated aqueous phase into the mixed reactor by nanofiltration of the separated aqueous phase with a nanofiltration membrane providing a retentate enriched in manganese complex and recycling all or a part of said retentate into the mixed reactor;
• wherein the combined hold-up time of aqueous phase in steps b) and c), defined as the ratio of the total volume occupied by aqueous phase in steps b) and c) to the volumetric flow rate of recycled separated aqueous phase, is less than 15 minutes.