Dehydrogenation of ethylbenzene to styrene with CO2 over iron oxide-based catalysts

This paper describes dehydrogenation reaction of ethylbenzene to styrene with CO(2) over iron oxide-based catalysts. Three catalysts of Fe(2)O(3)-MgO/gamma-Al(2)O(3), Fe(2)O(3)/MgAl(2)O(4) and MgFe(0.1)Al(1.9)O(4) with the same molar ratio of Mg/Fe/Al were prepared by impregnation and sol-gel methods. At 580 degrees C, the ethylbenzene conversion over MgFe(0.1)Al(1.9)O(4) kept a value of 40% during the time on stream of 20 h, whereas that over Fe(2)O(3)/MgAl(2)O(4) decreased rapidly from initial 50.0% to 27.4%. The properties of the catalysts were characterized by several techniques such as N(2) adsorption/desorption, X-ray diffraction, thermogravimetry, energy dispersive X-ray spectroscopy, Fourier transform-infrared spectroscopy, (57)Fe Mossbauer spectroscopy, temperature-programmed reduction, and temperature-programmed desorption of NH(3) and CO(2). It was found that the iron species of these catalysts are different. In MgFe(0.1)Al(1.9)O(4), all Fe(3+) species are incorporated in the spinel lattice. MgFe(0.1)Al(1.9)O(4) shows high catalytic activity and stability in ethylbenzene dehydrogenation reaction with CO(2). Moreover, the weak surface acidity of MgFe(0.1)Al(1.9)O(4) prevents from the carbon formation during the reaction. (C) 2010 Elsevier B.V. All rights reserved.