Phenol Production Kinetic Model in the Cyclohexanol Dehydrogenation Process

A kinetic model of phenol formation in the process of dehydrogenation of cyclohexanol to cyclohexanone has been developed and validated, including variables such as the temperature and the concentration of reactants and products. Catalytic dehydrogenation of cyclohexanol to cyclohexanone in the gas phase was conducted at atmospheric pressure in a continuous flow fixed-bed reactor (T = 220, 250, and 290 °C; W/Q L ratios from 102 to 1773 g cat h kg ―1 ). A commercial copper zinc oxide catalyst was employed. The kinetics of phenol formation, the main process impurity, were determined after discrimination of a kinetic model of the dehydrogenation of cyclohexanol to cyclohexanone. Weak adsorption of hydrogen on the copper catalyst was confirmed. Different reaction pathways for phenol formation were studied. The results suggested that phenol is obtained from cyclohexanone. This model was validated by the study of the reaction with pure cyclohexanone. Phenol production predicted by the proposed model fitted quite well with the experimental data. The estimated activation energy of phenol formation was 113.6 kJ/mol.