Abstract
? 2022 Elsevier B.V.A green and solvent-free aerobic protocol for ethybenzene (EB) oxidation mediated by efficient and stable solid catalysts remains a big challenge. In the present study, we report a finding of phase-dependent reactivity of MnO2 materials with α, β, and δ phases, with the order of EB oxidation performance following δ-MnO2 > α-MnO2 > β-MnO2. A clear negative correlation exists between the reactivity and average oxidation state (AOS) value of Mn, while positive correlations can be found between the reactivity and (Mn2++Mn3+)/Mn4+ ratio and OII/OI ratio. DFT studies also validate that molecular oxygen can be adsorbed and activated much more easily over the δ-MnO2, contributing to the generation of active oxygen species. This work provides insights into the MnO2-based materials with different crystal phases for catalytic synthesis of high value-added chemicals.
NSTL
Elsevier