Reaction coupling of ethylbenzene dehydrogenation with water-gas shift

Based on the thermodynamic analysis of the coupling of ethylbenzene (EB) dehydrogenation to styrene (ST) with reverse water-gas shift, the dehydrogenation of EB in the presence of CO2 over different catalysts was carried out. The conversion of EB is greatly improved by the reaction coupling due to the simultaneous elimination of the hydrogen produced by the dehydrogenation. Iron and vanadium supported on activated carbon were suggested to be possible catalysts. With the addition of alkali, alkaline earth, or rare-earth elements, high EB conversion (50-60%) and selectivity to ST (95-98%) were observed at 823 K. X-ray diffraction analysis indicated that carbon dioxide plays an important role in keeping the iron species at high valence and therefore, maintaining the catalytic activity in the coupling reactions. Results also suggested that the magnetite formed during heat treatment is the active phase of the carbon-supported iron catalysts, and that the addition of promoters to catalysts leads to the higher dispersion of the active species. (C) 2002 Elsevier Science B.V. All rights reserved.