Abstract: The activities of hydrodesulfurization(HDS)and hydrogenation(HYD)for UFPAl₂O₃catalysts prepared by two methods,impregnation and supercritical fluid drying process,were determined in a continuous flow microreactor. It is shown that the catalytic properties and the dispersion of Mo species on alumina surface are greatly affected by the preparation method,as compared to that of ordinary Mo/Al₂O₃(prepared by impregnating ordinary γ-Al₂O₃with molybdenum salt),the HDS activities of UFP-Mo/Al₂O₃(prepared by implregnating UFPalumina with Mo salt)are considerably high under the same condition. So do the HYD activities. It is also indicated from TPR,LRS and XRD that the Mo loading at which bulk MoO₃phase emerge for UFP-Mo/Al₂O₃is considerably higher than that for ordinary Mo/Al₂O₃catalysts,implying that using UFP-Al₂O₃and supercritical fluid drying process favor the dispersion of Mo species onto the surface of alumina.

Key words: UFP-Mo/Al₂O₃, TPR, Reduction behavior, Hydrodesulfurization, Hydrogenation