Stabilization of alkaline promoters in the structure of iron-oxide dehydrogenation catalysts

Resumo

A series of mixed polyferrites of β"-alumina type M₂Fe^IIFe_11−q^IIILn_qO₁₇, where q = 0.1–1.0; M = K, Cs, Rb; and Ln = Sc, Y, Ce, Sm, were synthesized. Their cation and electron conductivities and catalytic activity in the conversion of ethylbenzene into styrene were measured, and the relative chemical stability was determined. The mechanism of stabilization of the alkaline promoter in the catalyst structure during the doping of mixed potassium–cesium polyferrites with rare-earth oxides was considered. The requirements for the doping agent were formulated. The most promising way of stabilizing the alkaline promoter in a mixed potassium–cesium polyferrite system was shown to be the introduction of samarium oxide in amounts corresponding to q = 0.25–0.30, which is no more than 1.5 wt % based on the catalyst formulation.