Propylene epoxidation with hydrogen peroxide and titanium silicalite catalyst: Activity, deactivation and regeneration of the catalyst

The epoxidation of propene with hydrogen peroxide and a titanium silicalite catalyst with MFI structure was investigated in detail. The relationship between catalytic activity and propylene oxide selectivity can be explained by the acidification of water coordinated to the active titanium site and its reversible deprotonation to an ate complex, which inhibits the formation of the active species for epoxidation. Pretreatment of the catalyst with neutral or acidic salts improves the propylene oxide selectivity without affecting the catalytic activity. Catalyst deactivation occurs by blocking of the zeolite micropores with propylene oxide oligomers. The deactivated catalyst can be regenerated by refluxing with dilute hydrogen peroxide.