Role of the Fe oxidation states on the catalytic oxy-dehydrogenation of ethylbenzene using CO2 as a soft oxidant over FeOX/carbon-alumina

Iron oxide (FeOx) supported on 1:3 carbon-alumina (ICA) was prepared by wet impregnation method. Oxidized and reduced forms of Fe in ICA catalyst were achieved by diluted H2O2 and hydrazine hydrate treatments, respectively. Three different oxidation states of Fe present in magnetite (Fe2+ and Fe3+), hematite (Fe3+) and wustite (Fe2+) were confirmed by XPS, powder-XRD, H-2-TPR, TGA, NH3-TPD and N-2-physisorption analysis. Among the synthesized catalysts, in comparison with hematite and wustite phases, magnetite phase offered high catalytic activity in ethylbenzene dehydrogenation reaction. The presence of CO2 in the reaction mixture was found to leave intact the activated carbon support structure.