0 1 to 5 wt with a high circulation rate of the reaction mixture from reactor 1 to reactor 13 to assure reasonable rates of reaction and high reaction selectivity propylene reactant is introduced into reactor 13 via line 14 a c 3 splitter 15 is provided which separates a mixed c 3 fraction introduced via line 16 into a propane stream removed via line 17 and the propylene feed to reactor 13 also fed to reactor 13 via lines 14 and 18 is a solvent stream containing absorbed components from absorber 8 in reactor 13 propylene oxide is formed by reaction of propylene and the hydrogen peroxide from reactor 1 the reaction taking place in the catalyst solvent reaction mixture slurry from reactor 1 an overhead stream which comprises various components such as oxygen hydrogen propylene and propylene oxide product is separated via line 19 and passed to a separation and recovery facility not shown wherein the various components are recovered and where applicable recycled the slurry reaction mixture is removed from reactor 13 via line 20 and passed to filter 21 wherein a partial filtration takes place that is solids are separated from a portion of the reaction mixture and this portion from which solids have been separated is removed via line 22 the solids u2014 free stream is passed to conventional treatment.