Three stage propylene oxide process

1. Field of the Invention A three stage process for producing propylene oxide from propylene, oxygen, and hydrogen. The first reaction step is the oxidation of isopropanol/water with molecular oxygen in a reaction-distillation column (approx. 500 psi and 350° F.), to produce hydrogen peroxide and acetone. The column is configured with an upper high liquid holdup reaction zone and a lower short residence time stripping zone. Inert gas circulating through the column effects separation of the hydrogen peroxide as part of the bottoms fraction and acetone as part of the distillate fraction. The liquid part of the distillate fraction comprising acetone, isopropanol and water is then reacted with hydrogen (second reaction step) under reactive-distillation conditions to convert the contained acetone back to isopropanol for subsequent recycle to the first reaction step. The third reaction step is the epoxidation of propylene (in stoichiometric excess) with the hydrogen peroxide solution in the presence of a titanium silicalite catalyst. The reaction is performed in a series of fixed bed adiabatic reactors with intercooling. Product separation is by conventional distillation. Unreacted propylene is recycled to the epoxidation step and water/isopropanol to the first reaction step.