CATALYTIC EPOXIDATION OF CICLOHEXENE WITH ETHYLBENZENE HYDROPEROXIDE USING MOLYBDENUM HETEROGENEOUS CATALYST

摘要

The addition of molybdenum catalysts of the WE series occurs by the formation of a brown precipitate on the support surface, while Mo catalysts of THF series seams to takes place through reaction between molybdenum precursor and OH groups of silica surface Molybdenum species present on WE samples trend to form low disperse species with crystalline structure. The main part of the molybdenum is present as Mo(V) while samples prepared with THF yield more disperse Mo species and XPS analysis shows that Mo(V) and Mo(VI) are present on the catalysts. The heterogeneous catalysts are active in the epoxidation of cyclohexene with TBHP. However the two series display different behavior: samples prepared with THF are more active than its WE counterparts. The epoxide selectivity of heterogeneous catalysts under severe reaction conditions is higher than the homogenous reference catalyst. THF3 catalyst is a very good catalyst under standard reaction conditions with a very high yield to epoxide.