Mg–Zn and Mn–Zn Ferrites Derived from Coil Core Materials as New Phenol Methylation Catalysts

A catalytic phenol methylation study on two ferrospinel materials (Mg0.63Zn0.37)(Mn0.1Fe1.8)O3.85 (hereafter Mg–Zn) and (Mn0.55Zn0.35Fe0.1)Fe2O4 (hereafter Mn–Zn) was performed. The reaction was carried out in the gas phase in a continuous manner with the feed composition of phenol, methanol, and water in molar ratio 1:5:1. Both ferrites are active in the studied reaction. The alkylation of phenol with methanol led to the selective production of o-methylated phenol derivatives, i.e., o-cresol and 2,6-xylenol. However, both catalysts markedly differ in terms of activity. Different synergy effects on both catalysts cannot be a sufficient explanation. These materials do not differ significantly either in their susceptibility to reduction or in their Lewis type acidity. Because their microstructure differs significantly, a size effect may therefore be responsible for the differences in activity.