Ethylbenzene dehydrogenation with CO2 over Fe-doped MgAl2O4 spinel catalysts: Synergy effect between Fe2+ and Fe3+

Abstract Fe-doped MgAl 2 O 4 spinel catalyst of MgFe 0.1 Al 1.9 O 4 and supported catalyst of Fe 2 O 3 –MgO/γ-Al 2 O 3 for ethylbenzene dehydrogenation in the presence of CO 2 were studied by Mossbauer spectroscopy (MS) combining with the partial reduction method in the presence of H 2 , and the catalytic activity of the ferrous iron species was discussed. The results showed that the catalytic performance of Fe 3+ existing in spinel is superior to α-Fe 2 O 3 , and the synergistic effect between Fe 2+ and Fe 3+ might indeed increase the catalytic activity since Fe 2+ –O 2− formed in the process of reduction has moderate basicity, which was more favorable for desorption of CO 2 compared with Mg 2+ –O 2− . The reduced MgFe 0.1 Al 1.9 O 4 containing Fe 2+ of around 25% exhibits much higher catalytic activity than unreduced catalyst, with improved styrene yield nearly 2 times to 45.0%. Mg x Fe 1− x O as another ferrous iron species formed in the reduction process of Fe 2 O 3 –MgO/γ-Al 2 O 3 showed inconspicuously catalytic activity.