Effect of titanium active site location on activity of phase boundary catalyst particles for alkene epoxidation with aqueous hydrogen peroxide

Epoxidation of 1-octene with hydrogen peroxide at room temperature was examined using bimodal zeolite particles, in which some of the external surfaces some were covered with hydrophobic alkyl groups and the rest were left hydrophilic. When bimodal titanium-loaded NaY were added to a mixture of aqueous hydrogen peroxide and 1-octene, these particles could be assembled just at the liquid-liquid phase boundary, resulting in the formation of a particulate film, and efficiently catalyzed the epoxidation of 1-octene even without agitation. On the other hand, when TS-1 particles in which the active titanium species located mainly inside the pore system were used, there were no significant effects of partial modification on catalytic activity under the conditions of both stirring and no stirring. These results suggested that titanium species located on the external surfaces of particles were dominantly effective for the observed phase boundary catalytic system.