Process for making propene oxide

A process for making propene oxide involves reacting propene with hydrogen peroxide in the presence of methanol, a titanium zeolite epoxidation catalyst, and nitrogen containing compounds present in an amount of from 100 to 3000 mg/kg of hydrogen peroxide. Non-reacted propene is separated from the reaction mixture; the propene depleted reaction mixture is continuously distilled in a distillation column providing an overhead product stream containing propene oxide and methanol and a bottoms product stream; and propene oxide is separated from the overhead product stream. An acid is added to the propane depleted reaction mixture and/or to the distillation column at the same level or above the feed point for the propene depleted reaction mixture and/or contacted to the feed to the distillation column to provide an apparent pH in the bottoms product stream of from 3 to 4.5, which reduces the nitrogen content of the separated propene oxide.