Process for the preparation of propylene oxide

A process for preparing propylene oxide, comprising:

• (i) preparing a liquid feed stream comprising propene, hydrogen peroxide, acetonitrile, water, and dissolved potassium dihydrogen phosphate;
• (ii) feeding the liquid feed stream into an epoxidation reactor comprising a catalyst comprising a titanium zeolite of framework structure MWW;
• (iii) subjecting the liquid feed stream to epoxidation reaction conditions in the epoxidation reactor to obtain a reaction mixture comprising propylene oxide, acetonitrile, water, and potassium dihydrogen phosphate;
• (iv) removing the reaction mixture as an effluent stream from the epoxidation reactor;
• and
• (v) separating the propylene oxide from the effluent stream;
• wherein
• operations (i) to (v) are conducted as a continuous method, and
• in the liquid feed stream:
• a concentration of the dissolved potassium dihydrogen phosphate is at least 10% of a solubility limit of potassium dihydrogen phosphate in the liquid feed stream.