| dc.description.abstract | In this work, zirconium oxide (ZrO2) was used as a catalyst support. ZrO2 supported nanosized Au catalysts (Au/ZrO2) were prepared by the deposition-precipitation (DP) and co-precipitation method (CP). The supported Au catalysts were characterized by inductively coupled plasma-atomic emission spectrometer (ICP-AES), X-ray diffraction (XRD), thermogravimetric analyzer (TGA), nitrogen adsorption method, scanning electron microcopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS).
The thermal decomposition of the Au catalyst precursor starts above 698K. The specific surface area of the calcined catalysts prepared by CP method decreases with increasing the Au loading but catalysts prepared by DP method do not show any difference. From the image of TEM, we can see the black spherical Au crystallites clearly and good dispersion in both two preparation methods. Furthermore, the mean size of Au crystallites increases with an increase in calcination temperature only occurring in Au/ZrO2 prepared by CP method. In XPS analysis, Au catalysts prepared by DP method shows that not only have metallic Au but also oxidative Au in catalysts surface. As calcination temperature is getting higher, the ratio of metallic Au to ionic Au becomes larger.
Zirconium oxide supported Au catalysts was tested by the partial oxidation of methanol (POM) at 503-563K. The results indicate that the optimal preparation method and operating conditions are DP method, 2 wt% in Au loading, 573 K in calcination temperature, and 563 K in reaction temperature.
Compare to copper and palladium catalysts in POM reaction, Au/ZrO2 catalysts display good activity and hydrogen selectivity. Furthermore, Au/ZrO2 catalysts show no CO present. Nanosized Au/ZrO2 may have an opportunity to apply in proton exchange membrane fuel cell. | en_US |