The catalytic dehydrogenation of ethylbenzene and cumene over catalysts containing uranium oxide

The dehydrogenation of ethylbenzene to styrene and of cumene to α-methylstyrene has been investigated in a fixed bed reactor over bismuth uranate Bi₂UO₆ and uranium oxide as catalysts, at temperatures from 420 to 520 °C. Selectivities of 97% at a conversion of 38% for styrene and of 96% at a conversion of 66% for α-methylstyrene have been obtained in this study. Under reaction conditions Bi₂UO₆ loses 67 wt% of its oxygen and metallic bismuth is formed. Uranium oxide is reduced to UO₂. The reaction pattern on both catalysts changes during the reduction. This investigation is mainly concerned with the performance of the reduced catalysts. A kinetic model, which takes into account the chemisorption of the saturated reactants and of the unsaturated reaction products, has been used to interpret the experimental data. Energies of activation are 34 kcal mol^-1 for the ethylbenzene dehydrogenation and 27 kcal mol^-1 for the cumene dehydrogenation. By-products formed from ethylbenzene are benzene and toluene, while cumene produces benzene, toluene, ethylbenzene and styrene.