Photo-catalytic selective organic transformations by Fe-doped octahedral molecular sieves (manganese oxide) nano-structure

Abstract

The future development of chemistry entails environment-friendly and energy-sustainable alternatives for organic transformations. Visible light photo-catalysis can address these challenges. Octahedral molecular sieve manganese oxide (cryptomelane, OMS-2) and Fe-doped OMS-2 nano-structures were prepared to be used as affective visible light photo-catalysts for the oxidation of cyclohexane. The photo-catalysts were prepared by reflux method (at 100°C, for 24 h) under atmospheric pressure by using different molar ratios of Fe/Mn (0, 0.03, 0.08 and 0.10). Several techniques such as X-ray diffraction, transmission electron microscopy, Fourier-transform infrared spectra, nitrogen adsorption/desorption isotherms and thermal analysis were performed for characterizing the structure and the morphology of the prepared samples. The results revealed that the Fe-OMS-2 samples have a well-crystalline cryptomelane framework. In addition, no peaks related to the Fe dopant were detected, indicating the incorporation of Fe species into the framework of cryptomelane. The main product of photo-catalytic oxidation reaction of cyclohexane is cyclohexanone with a selectivity of 100% after 3 h for highest conversion on using 0.08Fe-OMS-2 sample.

Keywords

• Cryptomelane
• Fe doping
• preparation
• characterization
• photocatalytic oxidation
• reaction mechanism