Strongly active and environmentally friendly WO3/C3N4 photocatalysts for converting cyclohexane to cyclohexanone under ambient conditions

Abstract

Abstract C–H bond activation under mild conditions remains a great challenge in the chemical industry, while catalytic cyclohexane oxidation is inefficient and often requires organic solvents and strong oxidants. This study constructed a C3N4/WO3 Z-type heterojunction catalyst to efficiently convert cyclohexane into cyclohexanone and cyclohexanol (KA oil) through aqueous phase oxidation by O2 under visible light irradiation. With strong redox performance and high photogenerated carrier separation ability, the proposed composite catalyst can produce the key active species for cyclohexane oxidation in the H2O–O2 system. The reaction mechanism was clarified through experiment and DFT theory calculation. Cyclohexane was converted into cyclohexyl radical under the action of ·OH, and ·O2 − converted most products into cyclohexanone. The catalyst can be recycled under optimized process conditions while reaching a KA oil yield of 139.73 μmol g−1 h−1 and a selectivity of 93.1%.

Keywords

• Selective oxidation
• Photocatalysis
• Z-type heterojunction
• KA oil
• Radical