Enhanced shape selective catalysis of mixed cyclic ketones in aerobic Baeyer-Villiger oxidation with magnetic Cu-Fe3O4 supported mesoporous silica microspheres

Abstract

Various strategies have been developed to improve the conversion for the Baeyer-Villiger oxidation. However, the catalytic effects of the Baeyer-Villiger oxidation for the mixed ketones are rarely reported, though it is also important for the natural and industrial separation processes. In this report, magnetite Cu modified Fe3O4 supported mesoporous silica microspheres (Cu-Fe3O4@mSiO2) have been successfully synthesized by two step direct hydrothermal method (DHT). Over 99% of cyclohexanone conversion was obtained with mild air oxidation and benzaldehyde as sacrificing agent over Cu-Fe3O4@mSiO2. The catalytic system also shows higher conversion rates for small molecular ketones in the mixed ketone reactants, which was attributed to the enhanced mass transfer effect and Fe-Cu composite active sites in the magnetite mesoporous silica microspheres. The catalyst could be recycled for four times with similar catalytic performance, which shows enhanced shape selectivity in aerobic Baeyer-Villiger oxidations for mixed cyclic ketones.