Baeyer-Villiger oxidation of cyclohexanone to ε-caprolactone over hydrotalcite-supported Sb catalyst

The Baeyer-Villiger (BV) oxidation of cyclohexanone to E-caprolactone is an attractive process cause poly(E-caprolactone) is one of the most commonly used biodegradable polymers. With the increase in ronmental concern, much more research is focused on developing efficient catalytic methods using green cheap oxidants like hydrogen peroxide instead of peroxycarboxylic acids. In this work, the Sb catalyst on hydrotalcite (HT) was prepared by wetness impregnation of calcined hydrotalcite with a solution of then dried and calcined at 450degreesC for 5 h. The samples were characterized by XRD and TG-DTG. The XRD sults suggested that the calcined Sb/HT recovered the original layered structure during the reaction process. BV oxidation of cyclohexanone to E-caprolactone on the Sb/HT catalyst was carried out in a three-necked flask equipped with a reflux condenser and a magnetical stirrer. The results indicated that 1.5% Sb/HT a high activity for the BV oxidation of cyclohexanone in the acetonitrile medium. The cyclohexanone was about 42% and the selectivity for E-caprolactone was over 94%. In a set of reuse experiments, there was most no reduction of the catalyst activity and the selectivity for E-caprolactone over the regenerated catalyst almost the same as that on the fresh catalyst.