Highly dispersive tetrahedral vanadium species on pure silica ZSM-12 zeolite boosting the selective oxidation of cyclohexane into cyclohexanone

Abstract

The selective oxidation of cyclohexane is a promising green route for the production of KA oil (cyclohexanol and cyclohexanone), but remains a huge challenge to design high-performing heterogeneous catalysts under mild conditions. Herein, a pure silica ZSM-12 (MTW topology) zeolite was applied as the support to immobilize highly dispersive tetrahedrally coordinated vanadium (V) species and the constructed catalyst 1%V/SZ-12 exhibited high efficiency in the fast and selective oxidation of cyclohexane into cyclohexanone with H₂O₂. The reaction completed within 30 s, affording the selectivity of 99% towards cyclohexanone and the extremely high turnover frequency (TOF) of 5,891 h⁻¹. 1%V/SZ-12 was facilely reused with stable activity and feasibly extended to the oxidation of various cyclohexane derivatives. The one-dimensional 12-membered ring microchannels contributed to the formation and accessibility of tetrahedrally coordinated high valent V⁵⁺ species as the robust active centers, which activated H₂O₂ to generate V–O–O·, the active oxygen species for the electrophilic attack on cyclohexane to produce cyclohexanone as the sole product.