Abstract: Palladium catalysts supported on spherical γ-Al2O3 and θ-Al2O3 with palladium loading of 0.3% were prepared with and without ultrasonic treatment during the impregnation step. Structural and physical properties of the catalysts were characterized by X-ray diffraction, N2 adsorption, and transmission electron microscopy. The effects of ultrasonic treatment on the Pd distribution and anthraquinone hydrogenation activity of the catalysts were investigated. The results show that the activity of the supported catalysts prepared with ultrasonic treatment for anthraquinone hydrogenation is higher than those without ultrasonic treatment. Compared with the Pd/γ-Al2O3 catalyst, the supported catalyst Pd/θ-Al2O3 prepared under the same condition of ultrasonic treatment during the impregnation step has higher catalytic activity and stability in anthraquinone hydrogenation.

Key words: ultrasonic impregnation, anthraquinone, hydrogenation, supported palladium catalyst, hydrogen peroxide, spherical alumina