Selective Oxidation of Cyclohexane to Cyclohexanol/Cyclohexanone by Surface Peroxo Species on Cu-Mesoporous TiO2

Selective oxidation of cyclohexane to cyclohexanol/ cyclohexanone (KA-oil) is an important chemical process, which is still constrained by low conversion and selectivity and high energy consumption. In this study, Cu-doped mesoporous TiO2 (Cu-MT) has been successfully synthesized via calcinating MIL125(Ti) doped with copper acetylacetonate, which shows high reactivity in selective oxidation of cyclohexane to KA-oil by persulfate (PS) with the desirable cyclohexane conversion of 16.8% and a selectivity of 98.0% under mild conditions and the low ratio of PS/cyclohexane of 1:1. A series of characterizations and density functional theory calculations reveal that the doped Cu(I,II) on Cu-MT is the reactive site for non-radical activation of PS with the moderate elongation of the O-O bond in PS, which then abstracts 1H (1H+ + 1e-) from cyclohexane to form Cy center dot and eventually KA-oil. This study gives new insight on the importance of moderately activated PS in selective oxidation of C-H.

Automated summary

Cu-doped mesoporous TiO2 (Cu-MT) was successfully synthesized and found to have high reactivity towards the selective oxidation of cyclohexane to cyclohexanol/cyclohexanone (KA-oil), achieving a conversion of 16.8% and selectivity of 98.0% under mild conditions with a low PS/cyclohexane ratio of 1:1. The importance of moderately activated persulfate (PS) in the selective oxidation of C-H bonds was revealed.