Low-temperature CO oxidation over Au/ZnO/SiO₂ catalysts: Some mechanism insights

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• 作者：Kun Qian ; Weixin Huang ; Jun Fang ; Shanshan Lv ; Bo He ; Zhiquan Jiang ; Shiqiang Wei
• 关键词：Au/ZnO/SiO₂ catalyst ; CO oxidation ; Reaction mechanism ; Metal– ; support interaction
• 刊名：Journal of Catalysis
• 出版年：2008
• 期刊代码：97_00219517
• 类别：ce
• 出版时间：25 April 2008
• 卷：255
• 期：2
• 页码：269-278
• 文件大小：849 K

摘要

We report a new type of supported Au catalyst active in low-temperature CO oxidation. Au/ZnO/SiO₂ catalysts were prepared by routine deposition–precipitation with ammonium hydroxide (Au/ZnO/SiO₂-NH₃) and aqueous solution of Na₂CO₃ (Au/ZnO/SiO₂-Na₂CO₃) as the precipitation agent. The catalysts were characterized by BET surface area, X-ray diffraction, transmission electron microscopy, X-ray photoemission spectroscopy, photoluminescence spectroscopy, and X-ray absorption spectroscopy. Au/ZnO/SiO₂-Na₂CO₃ is more active than Au/ZnO/SiO₂-NH₃, achieving a complete CO conversion at 303 K. The structures of Au nanoparticles and ZnO are strongly affected by the Au–ZnO interaction in Au/ZnO/SiO₂ catalysts. The Au–ZnO interaction is stronger, and thus the Au nanoparticles are more highly dispersed in Au/ZnO/SiO₂-Na₂CO₃ than in Au/ZnO/SiO₂-NH₃. Our results suggest that CO oxidation catalyzed by supported Au nanoparticles follows different mechanisms at low and high reaction temperatures and that a weakly chemisorbed species is involved in low-temperature CO oxidation.