In-depth understanding of the key to deactivation of TS-1 in epoxidation of allyl chloride to epichlorohydrin

We present an intensive study of the deactivation mechanism of titanosilicates in epoxidation of allyl chloride to epichlorohydrin. Besides the generally accepted physical deactivation of titanosilicates caused by pore blocking, epichlorohydrin is the primary factor contributing to the deactivation of titanosilicates, in which the epoxy group undergoes a ring-opening reaction to form the poisoning species-bidentate ether species. Besides the acidity of titanosilicates and titanosilicates/H2O2, the effect of the properties of reactants and products on the formation of bidentate ether species was investigated. The reactant allyl chloride is susceptible to ionization and the formation of new Brønsted acid, which accelerates the deactivation of titanosilicates. From the epoxide perspective, other groups in the vicinity of the epoxy group also have an effect on the formation of the bidentate ether species. In general, the formation of the bidentate ether species is promoted by the electron-donating groups and inhibited by the electron-absorbing groups.