The Synthesis Of Support Ceria By Hydrothermal Method And Catalytic Activity Of The Au/CeO₂ Catalysts For CO Oxidation

In this work, nano-ceria was prepared by hydrothermal method and was used as supports of catalysts. A series of supported gold catalysts were prepared by co-precipitation and deposition-precipitation methods, and the catalytic performance for CO oxidation reaction was investigated for the purpose to search the new gold catalysts system. The structures of catalysts were characterized by X-ray diffraction (XRD), transmission electronic microscopy (TEM) techniques, X-ray photoelectron spectroscopy (XPS), UV-visible DR spectrum (UV-VISDRS) and specific surface area (BET), etc. The factors of the influence of preparation method, hydrothermal temperature, gold contents in the loaded gold catalysts were studed. The physical and chemical natures of catalysts were discussed also.The main experimental results and conclusions are as following: gold is existed in highly dispersed state like cluster in these catalysts, in contrast, the CeO₂ support is well crystallized, and the fringes from (111) lattice plane of the support CeO₂ are easy to be observed in the TEM. Compared to the support CeO₂, the loaded gold catalyst exhibited an excellent low-temperature catalytic activity toward CO oxidation reaction. In the studied range of gold content, the catalytic activity increases with the gold content. Especially, for the Au/CeO₂-HDP catalyst, in which gold content is 0.52wt.%, the complete oxidation (100%CO conversion) is achieved at 20℃, while the CO conversion over the support at 20℃is less as 1% and the complete oxidation was higher upto 340℃.In this work, correlations between the gold species of cationic and nano metallic and the activity of CO oxidation on the Au/CeO₂ catalysts is discussed.