Low-Temperature Water-Gas Shift Reaction over Au/ZrO2 Catalysts Using Hydrothermally Synthesized Zirconia as Supports

Au/ZrO2 catalysts with a nominal gold loading of 1.0% were prepared by a deposition-precipitation method employing a series of ZrO2 samples synthesized by a convenient hydrothermal route as supports. These catalysts were evaluated for low-temperature water-gas shift reaction under a model reformed methanol gas atmosphere. The effect of the hydrothermal synthesis temperature of zirconia on the catalytic activity of Au/ZrO2 was investigated. The optimal hydrothermal synthesis temperature of ZrO2 was 150 degrees C. The corresponding catalyst offers a CO conversion of 87% at a reaction temperature of 240 degrees C, which is significantly higher than that of the previously reported Au/Fe2O3, Au/CeO2, and Au/CeZrO4 catalysts. The Au/ZrO2 catalysts were characterized by X-ray diffraction, atomic absorption spectrometry, N-2-physisorption, and scanning electron microscopy. The results indicate that the catalytic performance of the Au/ZrO2 catalysts is mainly influenced by the morphology and pore structure of the ZrO2 that was hydrothermally synthesized at different temperatures. A uniform nanodisk morphology and increase in the pore volume and pore diameter of the ZrO2 particles lead to a higher catalytic activity of the Au/ZrO2 catalyst.