Hydrogen Peroxide Route to Propylene Oxide

The epoxidation of propylene with hydrogen peroxide has been implemented to pilot plant scale (2,000 t/a) by EniChem. The reaction is catalyzed by titanium silicalite-1 (TS-1). Although TS-1 has similar composition to the Ti/Si02 developed by Shell for the epoxidation of propylene with organic hydroperoxides ca. 2.5 wt% Ti, as Ti02) the reactivity is quite different. TS-1 prefers H2O2 and protic solvents, and is almost inactive with hydroperoxides or in apolar media. The reverse holds for Ti/Si02. The reason is found in the different 

Using hydrogen peroxide for the manufacture of propylene oxide means that water is co-produced in the reaction and no by-product needs to be disposed of or utilized. The reaction is carried out in a dilute solution of hydrogen peroxide ( 10 wt%) in aqueous methanol, below 60°C and moderate pressure. The reaction is fast even with 1 % H2O2. 

Box 3 Epoxidation of Higher Olefins with Hydrogen Peroxide 

The hydrogen peroxide process is characterized by lower environmental impact, a simpler process scheme and lower investment. However hydrogen peroxide is relatively expensive and still produced in plants with relatively low nameplate capacities, though the construction of a 300 kt/a propylene oxide plant has been announced by Dow Chemical and BASF. 

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