Influence of cation distribution of ZnFe2O4 on its catalytic activity of phenol hydroxylation with H2O2

The spinel ferrite exhibits a good catalytic performance in phenol hydroxylation by H2O2 to dihydroxybenzene. ZnFe2O4 was synthesized by co-precipitation and hydrothermal methods. The catalysts were characterized by means of Mossbauer spectroscopy, XRD and ESR techniques. The results of Mossbauer spectra, XRD and ESR all indicate that ZnFe2O4 synthesized from hydrothermal processing is the normal spinel structure, while ZnFe2O4 synthesized from co-precipitation method is partly inverse spinel with a substantial displacement of Fe3+ cations to A sites and Zn2+ cations into B sites of the cubic closepacked anionic sublattice. We found that the distribution of cations on tetrahedral and octahedral sites in zinc ferrites was different between the catalysts prepared by hydrothermal and co-precipitation methods, and the catalytic activity was influenced by the distribution of cations.