Microwave-accelerated solvent-free aerobic oxidation of benzyl alcohol over efficient and reusable manganese oxides

A new facile and cost-effective process involving the solvent-free oxidation of benzyl alcohol using molecular oxygen as oxidant under controlled microwave irradiation has been developed for the production of chlorine-free benzaldehyde. Influence of different catalyst parameters (different manganese oxides and other kinds of transition metal oxides) and reaction conditions (reaction period and temperature) on the process performance has been studied. Under optimized reaction conditions, the MnO2 catalyst showed a superior catalytic performance in the highly selective oxidation of benzyl alcohol as compared to other manganese oxide materials such as MnO, Mn2O3 and Mn3O4. Moreover, a very stable catalytic activity as a function of cycling test was observed for the MnO2 catalyst.