Abstract: Fe-K-based catalysts with MgO and CaO as promoters were prepared, and their catalytic performance for dehydrogenation of ethylbenzene to styrene was examined in a fixed-bed reactor. The effects of MgO and CaO on the catalysts were characterized by means of SEM, XRD, TPR, and Mssbauer spectroscopy. The catalyst activity was improved by the substitution of Mg2+for Fe3+, and the formation temperature of the active precursor, K2Fe22O34, could be decreased owing to the solid solution of magnesium ferrite on the Fe-K-Mg-based catalyst. The crystallization degree and the selectivity for styrene were improved on the Fe-K-Ca-based catalyst, which was due to the CaO in/on the sill-like crystallites of K2Fe22O34. Furthermore, the reduction of Fe3+was prevented, and the structural stability of the catalyst was enhanced by the CaO promoter.

Key words: ethylbenzene, dehydrogenation, styrene, magnesia, calcium oxide, promoter, ironic oxide, potassium oxide, composite oxide