Catalytic properties and chemical stability of potassium polyferrites with the addition of four-charged cations

Abstract

In order to elucidate the effect exerted by the addition of four-charged cations on the composition, chemical stability and catalytic properties, samples of potassium polyferrites with the β′′-alumina type structure of the composition K2FeII1+qFeIII10–2q MeqIVO17, where Me is Ce, Ti, Zr, and q = 0÷1.0, were synthesized. The mechanism of the effect of four-charged cations on the activity, selectivity of action and corrosion resistance of β′′-potassium polyferrite has been determined. Polyferrites doped with four-charged cations are characterized by a decrease in the specific rate of styrene formation and an increase in the selectivity of action in the ethylbenzene dehydrogenation reaction. The destabilizing effect of titanium additives is revealed, which is expressed in facilitating the emission of an alkali metal from the crystal lattice of polyferrite. Cerium additives lead to the destruction of the polyferrite structure due to the reduction of Ce4+ → Се3+ at the q parameter values above 0.6. Zirconium additives do not reduce the corrosion resistance of ferrite systems under the conditions of the dehydrogenation reaction.