Fe-Supported SBA-16 Type Cagelike Mesoporous Silica with Enhanced Catalytic Activity for Direct Hydroxylation of Benzene to Phenol

In this work, an Fe-supported cagelike mesoporous silica type SBA-16 catalyst (Fe/SBA-16) was successfully synthesized using iron nitrate as the precursor through a simple impregnation method. Results of X-ray diffraction, N 2 adsorption–desorption, transmission electron microscopy, and elemental mapping analysis showed that the mesoporous structure of the support was retained during catalyst preparation and that iron nanoparticles were dispersed on the SBA-16 surface. Moreover, ultraviolet–visible and X-ray photoelectron spectroscopic studies revealed that the iron(III) oxidation state was dominant in the Fe-supported cagelike mesoporous silica. It was found that the Fe/SBA-16 was an appropriate catalyst for the benzene hydroxylation to phenol using H 2 O 2 as the oxidant. The effects on the catalytic performance of operating parameters such as the amount of H 2 O 2, reaction temperature, reaction time, and catalyst dosage were investigated. Under the optimized conditions, 11.7% phenol yield and 96.4% selectivity to phenol were obtained; in addition, the catalyst could be recycled at least three times.