Gas phase hydrogenation of benzene on supported nickel catalyst

Abstract

The kinetics of benzene hydrogenation over a nickel-kieselguhr catalyst was studied in a differential flow microreactor. Temperatures ranged from 392.2 to 468.2 K, benzene partial pressures from 22.66 to 280 Pa, hydrogen partial pressures from 72.39 to 122.79 kPa, and cyclohexane partial pressures from 5.33 to 40 Pa. Cyclohexane was the only product of the reaction. The results were consistent with a mechanism in which all hydrogen addition steps were assumed to have the same rate constant and to form a set of slow steps. This mechanism could predict the maximum in the hydrogenation rate observed at about 458 K. A temperature-programmed desorption study of hydrogen chemisorbed on the catalyst indicated a number of desorption peaks between 358 and 600 K, one of which was coincident with the rate maximum.