KINETICS OF ETHYLBENZENE HYDROGENATION ON NI AL2O3/

The gas-phase hydrogenation kinetics of ethylbenzene on Ni/Al2O3 was i nvestigated in a differential microreactor at atmospheric pressure and 130-190 degrees C. Rapid deactivation of the catalyst complicated the steady-state measurements. Reaction orders were near zero for the aro matic compound and between 1.2 (130 degrees C) and 2.3 (190 degrees C) for hydrogen. A rate maximum was observed at 160-175 degrees C, depen ding on the concentration ratio of the reactants. Mechanistic modellin g suggested that the reaction rate is governed by three steps of pairw ise sequential addition of hydrogen atoms to adsorbed ethylbenzene. Th e partially hydrogenated surface intermediates were proposed to have a romatic character. The physical reasonability of the model parameters was discussed.