Dehydrogenation of cyclohenxanol to cyclohexanone

Abstract

The dehydrogenation of cyclohexanol to cyclohexanone has been studied in detail. The thermodynamic equilibrium constants at various temperatures have been collected from literature and the equilibrium conversions have been calculated for various temperatures. At higher temperatures, side reactions have become predominant. The catalysts chosen for detailed study are selected from a large number on the basis of selectivity and activity considerations. Physical steps like internal and external diffusions have been eliminated by proper choice of particle size and the height of the catalyst bed. The complete kinetic data have been collected in a static bed integral type reactor under isothermal conditions. The variables studied are time factor, feed composition and temperature. Conversion increases with increasing time factor up to the highest temperature, 300°C, studied. The data have been correlated by a fourth degree polynomial in (W/P). Reaction rate at any instant can be obtained by the analytical differentiation of the polynomial with respect to (W/P). A rate equation has been developed on the basis of first order forward and second order backward reaction. Using Arrhenius relationship the frequency factor and activation energy have been calculated. Calculated conversions have been compared with experimental conversions and it was found that the data fit the final design equation with a standard deviation of ±12.5%. Rate equation has also been developed on the basis of Hougen-Watson approach. Mixed feed data have been used for this. Temperature dependence of apparent reaction velocity constant and adsorption equilibrium constant have been tested by Arrhenius relationship. Finally, experimental rates have been compared with calculated rates and it is found that the equation represents the data fairly well.