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 °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.

摘要采用一种简便的水热法合成了一系列 ZrO2, 并采用沉积-沉淀法制得相应 1.0% Au/ZrO2 催化剂, 在模拟甲醇重整气气氛下评价了它们的低温水煤气变换 (WGS) 反应催化性能. 结果发现, 于 150 oC 水热合成的 ZrO2 负载的 Au 催化剂活性最佳, 240 oC 反应时 CO 转化率达 87%, 明显高于相同反应条件下 Au 负载量较高的 Au/Fe2O3, Au/CeO2 及 Au/CeZrO4 催化剂. 采用 X 射线衍射、原子吸收光谱、N2 物理吸脱附及扫描电子显微镜等手段对样品进行了表征. 结果表明, Au/ZrO2 催化剂的总孔体积及平均孔径越大、圆形片状形貌越规整, 其低温 WGS 催化活性就越高.

Au/ZrO2 catalysts with hydrothermally synthesized ZrO2 as supports show excellent catalytic activity for the low-temperature WGS reaction. The nanodisk morphology and the larger pore volume and size benefit the performance of the Au/ZrO2 catalysts.Figure optionsDownload as PowerPoint slide