Direct synthesis of propylene oxide

Propylene was epoxidized, (1.8-11):1 by moles, with aq. 33% H2O2 in aq. 77-92% MeOH or aq. 92% 2-PrOH as solvent over a MFI structure titanosilicalite as catalyst, 10 and 19 (or 37) g/kg soln., resp., at 40-60 degrees C for 25-45 min to make H2O2 convert in min. 90 mol %. In MeOH, the epoxidation was faster and selective in 99%; by-products (1- and 2-methoxy-propanois and propylene glycol traces, but neither HCOH nor Me formate) were practically unaffected by temp. and oxidant excess. About 2-4% of H2O2 broke into H2O and O-2. Higher mole ratios were preferable; low (1.8-3) were ineffective. In 2-PrOH, the by-products were 1-(1-methylethoxy)-2-propanol, 2-isopropoxy-1-propanol, propylene glycol (twice as much as the glycolethers), and acetone; selectivity toward glycol-ethers was always similar to 2%. At 40-60 degrees C and with mole ratios raised, 3-11, selectivity toward PO rose from 92 to 95.5 mol %. PO oligomers deactivated the catalyst, but calcination at 550 degrees C rejuvenated it with only slight selectivity sacrificed.