Gas-Phase Hydroxylation of Chlorobenzene Over Cu-HZSM-5 and Catalyst Deactivation

Catalytic activity and deactivation of the Cu-HZSM-5 catalyst used in the gas-phase hydroxylation of chlorobenzene to phenol were studied. Under the conditions of 773 K and water/chlorobenzene volume ratio of 3, a chlorobenzene conversion of 82.4% and a phenol selectivity of 98.2% were obtained. Deactivation of the Cu-HZSM-5 catalyst was observed during the reaction. X-ray diffraction, N2 volumetric adsorption, energy dispersive X-ray spectroscopy, and infrared spectroscopy of adsorbed pyridine were performed on fresh, used, and regenerated catalysts to study the reaction and catalyst deactivation mechanisms. The leaching of copper from the catalyst, framework dealumination of HZSM-5, and coking were the main causes of the catalyst deactivation.