Synthesis of mesoporous NiO/Bi2WO6 nanocomposite for selective oxidation of alcohols

Abstract

Mesoporous NiO/Bi2WO6 nanocomposite has been synthesized and found to be an efficient catalyst for the oxidation of primary and secondary benzylic alcohols under mild conditions. The mean particle size of the nanocomposite, determined by SEM and TEM, is about 60 nm. The BET analysis shows a narrow pore-size distribution of 6–9 nm and specific surface area of 73 m2g-1, which is much higher than its individual components, i.e. Bi2WO6 and NiO nanoparticles. This mesoporous structure facilitates the access of bulky molecules to the active sites of the catalyst, increasing the catalytic activity. In this study, the effects of oxidant, reaction time, solvent, amount of catalyst, and catalyst reusability have been investigated. The results reveal that the synthesized nanocomposite shows a significant improvement in the oxidation of benzylic alcohols to their corresponding aldehydes under mild conditions with the selectivity over 99% and higher conversion percentage compared to its individual components. Additionally, the results of this study suggest that the conversions of substituted benzyl alcohols are dependent on the position of substituents on the ring. The catalyst can be recycled five times and reused for oxidation of alcohols without significant loss of activity.