Abstract: 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 °C. The corresponding catalyst offers a CO conversion of 87% at a reaction temperature of 240 °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, N₂-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.

Key words: hydrothermal method, hydrothermal synthesis temperature, gold, zirconia, supported catalyst, water-gas shift reaction