Characterization and catalytic application of homogeneous nano-composite oxides ZrO 2–Al 2O 3

Abstract

A series of ZrO 2–Al 2O 3 composite oxides with different ZrO 2 contents was prepared by means of a chemical precipitation method using ZrOCl 2·8H 2O and pseudoboehmite as starting materials. The structures of the samples have been investigated by powder X-ray diffraction (XRD) and transmission electron micrography (TEM), with thermogravimetry differential thermal analysis (TG-DTA and DTG) combined. The results showed that the synthesized materials consisted of ZrO 2 and Al 2O 3 nanosized particles and they existed as amorphous phase in the samples with insufficient contents of ZrO 2. The surface areas ( S BET), the pore volumes and the pore distributions were measured by nitrogen adsorption method, and a regular correlation between the pore distributions and contents of ZrO 2 was observed. NH 3-temperature programmed desorption (NH 3-TPD) was used to characterize the surface acidic properties of the samples. The investigation by X-ray photoelectron spectroscopy (XPS) indicated that there were interactions between ZrO 2 and Al 2O 3 in the composite oxides. The synthesized ZrO 2–Al 2O 3 samples were purposively used as the supports for hydrodesulfurization (HDS) process. The sulfided CoMo/ZrO 2–Al 2O 3 catalysts were tested in the HDS reaction of dibenzothiophene (DBT), and the results showed that the sulfided CoMo catalysts supported on the composite oxide with a suitable ZrO 2 content performed a higher HDS activity than that supported on alumina.