Reaction coupling in the new processes for producing styrene from ethylbenzene

The possibility of coupling the ethylbenzene dehydrogenation with water-gas shift, CO2 methanation, and nitrobenzene hydrogenation has been investigated thermodynamically. The chemical equilibria of these reactions have been calculated on the basis of the Soave-Redlich-Kwong equation of state, and the effects of the feed composition, temperature, and pressure upon ethylbenzene equilibrium conversion have been studied. It was found that the equilibrium conversion could be greatly enhanced by the reaction coupling, especially with nitrobenzene hydrogenation. When coupling with water-gas shift, the ethylbenzene equilibrium conversion can be elevated to 82.4% from 25.2% for the single ethylbenzene dehydrogenation at 550 degreesC. When coupling with nitrobenzene hydrogenation, the ethylbenzene equilibrium conversion can reach 98.5% at 400 degreesC, compared with the conversion of 3.5% at the same temperature for the single ethylbenzene dehydrogenation. The primary experiments on a series of catalysts also proved that the reaction coupling is an effective measure to improve the ethylbenzene dehydrogenation, although much more work is still necessary to develop proper catalysts for the coupling reactions.