Process for the epoxidation of propene to propylene oxide

A continuous process for the preparation of propylene oxide, comprising (i) providing a liquid feed stream comprising propene, hydrogen peroxide, methanol, water, at least one dissolved potassium salt of hydroxyethylidenediphosphonic acid and optionally propane; (ii) passing the liquid feed stream provided in (i) to an epoxidation reactor comprising a catalyst comprising a titanium zeolite of MFI type structure, and subjecting the liquid feed stream to epoxidation reaction conditions in the reactor of epoxidation, obtaining a reaction mixture comprising propylene oxide, methanol, water and the at least one potassium salt of dissolved hydroxyethylidenediphosphonic acid, and optionally propane; (iii) removing an effluent stream from the epoxidation reactor, the effluent stream comprising propylene oxide, methanol, water, at least a portion of at least one potassium salt of hydroxyethylidenediphosphonic acid and optionally propane.