High temperature catalytic dehydrogenation of ethylcyclohexane

Summary

• 1. An investigation has been made of the high temperature dehydrogeration of ethylcyclohexane and ethylbenzene in presence of two catalysts at different temperatures (495° and 547° and with and without a carbon dioxide diluent.

• 2. It has been found that the main products of the dehydrogenation of ethylcyclohexane are ethylbenzene and styrene. At the same time small amounts of unsaturated “by-products” are formed (probably ethylcyclohexene).

• 3. It has been shown that the ethylbenzene content of ethylcyclohexane catalyzates falls sharply as the molar velocity is increased, but the concentration of unsaturated products (mainly styrene) remains practically constant and is independent of the degree of azomatization of the ethylcyclohexane. The styrene content of the ethylbenzene dehydrogenation catalyzates also remains practically constant when the molar velocity is varied over a wide range, and it is several times as great as the concentration of unsaturated hydrocarbons in the ethylcyclohexane catalyzates.

• 4. It has been established, on the basis of these results, that the catalytic dehydrogenation of ethylcyclohexane proceeds in two stages: ethylcyclohexane → ethylbenzene → styrene.

• 5. It has been shown that identical dilution of ethylcyclohexane and ethylbenzene with carbon dioxide (a dilution of 2) leads to identical relative increase (by one third) in the content of unsaturated hydrocarbons in the catalyzates.

• 6. It has been suggested that the nondependence of the styrene content ethylcyclohexane catalyzates on the degree of aromization of the ethylcyclohexane results from the fact that the dehydrogenation of ethylbenzene formed from ethylcyclohexane, attains a state of thermodynamic equilibrium.