A one-step method for preparing Cr-doped SiO2: An efficient catalyst for the direct oxidation of cyclohexane to ketone-alcohol oil

A series of heterogeneous catalysts with Cr as an active component is prepared by an innovative in situ coprecipitation method. The prepared Cr/SiO2 catalyst has high catalytic activity, selectivity, and stability in the conversion of cyclohexane into ketone-alcohol oil using H2O2 as the oxidant under mild conditions, resulting in 54.59% cyclohexane conversion and 90.01% ketone-alcohol oil selectivity. The physical and chemical properties of the prepared materials are studied by X-ray diffraction, Fourier transform infrared, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption-desorption analysis (BET). The excellent performance of the Cr/SiO2-400 catalyst is due to the increase of low-valence chromium species and the intimate interaction between SiO2 and CrOx. In addition, the catalyst was easy to separate and maintained good catalytic activity even after four runs.